Actual source code: snes.c

  1: #include <petsc/private/snesimpl.h>
  2: #include <petscdmshell.h>
  3: #include <petscdraw.h>
  4: #include <petscds.h>
  5: #include <petscdmadaptor.h>
  6: #include <petscconvest.h>

  8: PetscBool         SNESRegisterAllCalled = PETSC_FALSE;
  9: PetscFunctionList SNESList              = NULL;

 11: /* Logging support */
 12: PetscClassId  SNES_CLASSID, DMSNES_CLASSID;
 13: PetscLogEvent SNES_Solve, SNES_SetUp, SNES_FunctionEval, SNES_JacobianEval, SNES_NGSEval, SNES_NGSFuncEval, SNES_NPCSolve, SNES_ObjectiveEval;

 15: /*@
 16:   SNESSetErrorIfNotConverged - Causes `SNESSolve()` to generate an error immediately if the solver has not converged.

 18:   Logically Collective

 20:   Input Parameters:
 21: + snes - iterative context obtained from `SNESCreate()`
 22: - flg  - `PETSC_TRUE` indicates you want the error generated

 24:   Options Database Key:
 25: . -snes_error_if_not_converged <true,false> - cause an immediate error condition and stop the program if the solver does not converge

 27:   Level: intermediate

 29:   Note:
 30:   Normally PETSc continues if a solver fails to converge, you can call `SNESGetConvergedReason()` after a `SNESSolve()`
 31:   to determine if it has converged. Otherwise the solution may be inaccurate or wrong

 33: .seealso: [](ch_snes), `SNES`, `SNESGetErrorIfNotConverged()`, `KSPGetErrorIfNotConverged()`, `KSPSetErrorIfNotConverged()`
 34: @*/
 35: PetscErrorCode SNESSetErrorIfNotConverged(SNES snes, PetscBool flg)
 36: {
 37:   PetscFunctionBegin;
 40:   snes->errorifnotconverged = flg;
 41:   PetscFunctionReturn(PETSC_SUCCESS);
 42: }

 44: /*@
 45:   SNESGetErrorIfNotConverged - Indicates if `SNESSolve()` will generate an error if the solver does not converge?

 47:   Not Collective

 49:   Input Parameter:
 50: . snes - iterative context obtained from `SNESCreate()`

 52:   Output Parameter:
 53: . flag - `PETSC_TRUE` if it will generate an error, else `PETSC_FALSE`

 55:   Level: intermediate

 57: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetErrorIfNotConverged()`, `KSPGetErrorIfNotConverged()`, `KSPSetErrorIfNotConverged()`
 58: @*/
 59: PetscErrorCode SNESGetErrorIfNotConverged(SNES snes, PetscBool *flag)
 60: {
 61:   PetscFunctionBegin;
 63:   PetscAssertPointer(flag, 2);
 64:   *flag = snes->errorifnotconverged;
 65:   PetscFunctionReturn(PETSC_SUCCESS);
 66: }

 68: /*@
 69:   SNESSetAlwaysComputesFinalResidual - tells the `SNES` to always compute the residual (nonlinear function value) at the final solution

 71:   Logically Collective

 73:   Input Parameters:
 74: + snes - the shell `SNES`
 75: - flg  - `PETSC_TRUE` to always compute the residual

 77:   Level: advanced

 79:   Note:
 80:   Some solvers (such as smoothers in a `SNESFAS`) do not need the residual computed at the final solution so skip computing it
 81:   to save time.

 83: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetAlwaysComputesFinalResidual()`
 84: @*/
 85: PetscErrorCode SNESSetAlwaysComputesFinalResidual(SNES snes, PetscBool flg)
 86: {
 87:   PetscFunctionBegin;
 89:   snes->alwayscomputesfinalresidual = flg;
 90:   PetscFunctionReturn(PETSC_SUCCESS);
 91: }

 93: /*@
 94:   SNESGetAlwaysComputesFinalResidual - checks if the `SNES` always computes the residual at the final solution

 96:   Logically Collective

 98:   Input Parameter:
 99: . snes - the `SNES` context

101:   Output Parameter:
102: . flg - `PETSC_TRUE` if the residual is computed

104:   Level: advanced

106: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetAlwaysComputesFinalResidual()`
107: @*/
108: PetscErrorCode SNESGetAlwaysComputesFinalResidual(SNES snes, PetscBool *flg)
109: {
110:   PetscFunctionBegin;
112:   *flg = snes->alwayscomputesfinalresidual;
113:   PetscFunctionReturn(PETSC_SUCCESS);
114: }

116: /*@
117:   SNESSetFunctionDomainError - tells `SNES` that the input vector, a proposed new solution, to your function you provided to `SNESSetFunction()` is not
118:   in the functions domain. For example, a step with negative pressure.

120:   Logically Collective

122:   Input Parameter:
123: . snes - the `SNES` context

125:   Level: advanced

127:   Notes:
128:   If this is called the `SNESSolve()` stops iterating and returns with a `SNESConvergedReason` of `SNES_DIVERGED_FUNCTION_DOMAIN`

130:   You should always call `SNESGetConvergedReason()` after each `SNESSolve()` and verify if the iteration converged (positive result) or diverged (negative result).

132:   You can direct `SNES` to avoid certain steps by using `SNESVISetVariableBounds()`, `SNESVISetComputeVariableBounds()` or
133:   `SNESLineSearchSetPreCheck()`, `SNESLineSearchSetPostCheck()`

135: .seealso: [](ch_snes), `SNESCreate()`, `SNESSetFunction()`, `SNESFunction`, `SNESSetJacobianDomainError()`, `SNESVISetVariableBounds()`,
136:           `SNESVISetComputeVariableBounds()`, `SNESLineSearchSetPreCheck()`, `SNESLineSearchSetPostCheck()`, `SNESConvergedReason`, `SNESGetConvergedReason()`
137: @*/
138: PetscErrorCode SNESSetFunctionDomainError(SNES snes)
139: {
140:   PetscFunctionBegin;
142:   PetscCheck(!snes->errorifnotconverged, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "User code indicates input vector is not in the function domain");
143:   snes->domainerror = PETSC_TRUE;
144:   PetscFunctionReturn(PETSC_SUCCESS);
145: }

147: /*@
148:   SNESSetJacobianDomainError - tells `SNES` that the function you provided to `SNESSetJacobian()` at the proposed step. For example there is a negative element transformation.

150:   Logically Collective

152:   Input Parameter:
153: . snes - the `SNES` context

155:   Level: advanced

157:   Notes:
158:   If this is called the `SNESSolve()` stops iterating and returns with a `SNESConvergedReason` of `SNES_DIVERGED_FUNCTION_DOMAIN`

160:   You should always call `SNESGetConvergedReason()` after each `SNESSolve()` and verify if the iteration converged (positive result) or diverged (negative result).

162:   You can direct `SNES` to avoid certain steps by using `SNESVISetVariableBounds()`, `SNESVISetComputeVariableBounds()` or
163:   `SNESLineSearchSetPreCheck()`, `SNESLineSearchSetPostCheck()`

165: .seealso: [](ch_snes), `SNESCreate()`, `SNESSetFunction()`, `SNESFunction()`, `SNESSetFunctionDomainError()`, `SNESVISetVariableBounds()`,
166:           `SNESVISetComputeVariableBounds()`, `SNESLineSearchSetPreCheck()`, `SNESLineSearchSetPostCheck()`, `SNESConvergedReason`, `SNESGetConvergedReason()`
167: @*/
168: PetscErrorCode SNESSetJacobianDomainError(SNES snes)
169: {
170:   PetscFunctionBegin;
172:   PetscCheck(!snes->errorifnotconverged, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "User code indicates computeJacobian does not make sense");
173:   snes->jacobiandomainerror = PETSC_TRUE;
174:   PetscFunctionReturn(PETSC_SUCCESS);
175: }

177: /*@
178:   SNESSetCheckJacobianDomainError - tells `SNESSolve()` whether to check if the user called `SNESSetJacobianDomainError()` Jacobian domain error after
179:   each Jacobian evaluation. By default, we check Jacobian domain error in the debug mode, and do not check it in the optimized mode.

181:   Logically Collective

183:   Input Parameters:
184: + snes - the `SNES` context
185: - flg  - indicates if or not to check Jacobian domain error after each Jacobian evaluation

187:   Level: advanced

189:   Note:
190:   Checks require one extra parallel synchronization for each Jacobian evaluation

192: .seealso: [](ch_snes), `SNES`, `SNESConvergedReason`, `SNESCreate()`, `SNESSetFunction()`, `SNESFunction()`, `SNESSetFunctionDomainError()`, `SNESGetCheckJacobianDomainError()`
193: @*/
194: PetscErrorCode SNESSetCheckJacobianDomainError(SNES snes, PetscBool flg)
195: {
196:   PetscFunctionBegin;
198:   snes->checkjacdomainerror = flg;
199:   PetscFunctionReturn(PETSC_SUCCESS);
200: }

202: /*@
203:   SNESGetCheckJacobianDomainError - Get an indicator whether or not we are checking Jacobian domain errors after each Jacobian evaluation.

205:   Logically Collective

207:   Input Parameter:
208: . snes - the `SNES` context

210:   Output Parameter:
211: . flg - `PETSC_FALSE` indicates that we don't check Jacobian domain errors after each Jacobian evaluation

213:   Level: advanced

215: .seealso: [](ch_snes), `SNES`, `SNESCreate()`, `SNESSetFunction()`, `SNESFunction()`, `SNESSetFunctionDomainError()`, `SNESSetCheckJacobianDomainError()`
216: @*/
217: PetscErrorCode SNESGetCheckJacobianDomainError(SNES snes, PetscBool *flg)
218: {
219:   PetscFunctionBegin;
221:   PetscAssertPointer(flg, 2);
222:   *flg = snes->checkjacdomainerror;
223:   PetscFunctionReturn(PETSC_SUCCESS);
224: }

226: /*@
227:   SNESGetFunctionDomainError - Gets the status of the domain error after a call to `SNESComputeFunction()`;

229:   Logically Collective

231:   Input Parameter:
232: . snes - the `SNES` context

234:   Output Parameter:
235: . domainerror - Set to `PETSC_TRUE` if there's a domain error; `PETSC_FALSE` otherwise.

237:   Level: developer

239: .seealso: [](ch_snes), `SNES`, `SNESSetFunctionDomainError()`, `SNESComputeFunction()`
240: @*/
241: PetscErrorCode SNESGetFunctionDomainError(SNES snes, PetscBool *domainerror)
242: {
243:   PetscFunctionBegin;
245:   PetscAssertPointer(domainerror, 2);
246:   *domainerror = snes->domainerror;
247:   PetscFunctionReturn(PETSC_SUCCESS);
248: }

250: /*@
251:   SNESGetJacobianDomainError - Gets the status of the Jacobian domain error after a call to `SNESComputeJacobian()`;

253:   Logically Collective

255:   Input Parameter:
256: . snes - the `SNES` context

258:   Output Parameter:
259: . domainerror - Set to `PETSC_TRUE` if there's a Jacobian domain error; `PETSC_FALSE` otherwise.

261:   Level: advanced

263: .seealso: [](ch_snes), `SNES`, `SNESSetFunctionDomainError()`, `SNESComputeFunction()`, `SNESGetFunctionDomainError()`
264: @*/
265: PetscErrorCode SNESGetJacobianDomainError(SNES snes, PetscBool *domainerror)
266: {
267:   PetscFunctionBegin;
269:   PetscAssertPointer(domainerror, 2);
270:   *domainerror = snes->jacobiandomainerror;
271:   PetscFunctionReturn(PETSC_SUCCESS);
272: }

274: /*@C
275:   SNESLoad - Loads a `SNES` that has been stored in `PETSCVIEWERBINARY` with `SNESView()`.

277:   Collective

279:   Input Parameters:
280: + snes   - the newly loaded `SNES`, this needs to have been created with `SNESCreate()` or
281:            some related function before a call to `SNESLoad()`.
282: - viewer - binary file viewer, obtained from `PetscViewerBinaryOpen()`

284:   Level: intermediate

286:   Note:
287:   The type is determined by the data in the file, any type set into the `SNES` before this call is ignored.

289: .seealso: [](ch_snes), `SNES`, `PetscViewer`, `SNESCreate()`, `SNESType`, `PetscViewerBinaryOpen()`, `SNESView()`, `MatLoad()`, `VecLoad()`
290: @*/
291: PetscErrorCode SNESLoad(SNES snes, PetscViewer viewer)
292: {
293:   PetscBool isbinary;
294:   PetscInt  classid;
295:   char      type[256];
296:   KSP       ksp;
297:   DM        dm;
298:   DMSNES    dmsnes;

300:   PetscFunctionBegin;
303:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
304:   PetscCheck(isbinary, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Invalid viewer; open viewer with PetscViewerBinaryOpen()");

306:   PetscCall(PetscViewerBinaryRead(viewer, &classid, 1, NULL, PETSC_INT));
307:   PetscCheck(classid == SNES_FILE_CLASSID, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_WRONG, "Not SNES next in file");
308:   PetscCall(PetscViewerBinaryRead(viewer, type, 256, NULL, PETSC_CHAR));
309:   PetscCall(SNESSetType(snes, type));
310:   PetscTryTypeMethod(snes, load, viewer);
311:   PetscCall(SNESGetDM(snes, &dm));
312:   PetscCall(DMGetDMSNES(dm, &dmsnes));
313:   PetscCall(DMSNESLoad(dmsnes, viewer));
314:   PetscCall(SNESGetKSP(snes, &ksp));
315:   PetscCall(KSPLoad(ksp, viewer));
316:   PetscFunctionReturn(PETSC_SUCCESS);
317: }

319: #include <petscdraw.h>
320: #if defined(PETSC_HAVE_SAWS)
321: #include <petscviewersaws.h>
322: #endif

324: /*@C
325:   SNESViewFromOptions - View a `SNES` based on values in the options database

327:   Collective

329:   Input Parameters:
330: + A    - the `SNES` context
331: . obj  - Optional object that provides the options prefix for the checks
332: - name - command line option

334:   Level: intermediate

336: .seealso: [](ch_snes), `SNES`, `SNESView`, `PetscObjectViewFromOptions()`, `SNESCreate()`
337: @*/
338: PetscErrorCode SNESViewFromOptions(SNES A, PetscObject obj, const char name[])
339: {
340:   PetscFunctionBegin;
342:   PetscCall(PetscObjectViewFromOptions((PetscObject)A, obj, name));
343:   PetscFunctionReturn(PETSC_SUCCESS);
344: }

346: PETSC_EXTERN PetscErrorCode SNESComputeJacobian_DMDA(SNES, Vec, Mat, Mat, void *);

348: /*@C
349:   SNESView - Prints or visualizes the `SNES` data structure.

351:   Collective

353:   Input Parameters:
354: + snes   - the `SNES` context
355: - viewer - the `PetscViewer`

357:   Options Database Key:
358: . -snes_view - Calls `SNESView()` at end of `SNESSolve()`

360:   Level: beginner

362:   Notes:
363:   The available visualization contexts include
364: +     `PETSC_VIEWER_STDOUT_SELF` - standard output (default)
365: -     `PETSC_VIEWER_STDOUT_WORLD` - synchronized standard
366:   output where only the first processor opens
367:   the file.  All other processors send their
368:   data to the first processor to print.

370:   The available formats include
371: +     `PETSC_VIEWER_DEFAULT` - standard output (default)
372: -     `PETSC_VIEWER_ASCII_INFO_DETAIL` - more verbose output for `SNESNASM`

374:   The user can open an alternative visualization context with
375:   `PetscViewerASCIIOpen()` - output to a specified file.

377:   In the debugger you can do "call `SNESView`(snes,0)" to display the `SNES` solver. (The same holds for any PETSc object viewer).

379: .seealso: [](ch_snes), `SNES`, `SNESLoad()`, `SNESCreate()`, `PetscViewerASCIIOpen()`
380: @*/
381: PetscErrorCode SNESView(SNES snes, PetscViewer viewer)
382: {
383:   SNESKSPEW     *kctx;
384:   KSP            ksp;
385:   SNESLineSearch linesearch;
386:   PetscBool      iascii, isstring, isbinary, isdraw;
387:   DMSNES         dmsnes;
388: #if defined(PETSC_HAVE_SAWS)
389:   PetscBool issaws;
390: #endif

392:   PetscFunctionBegin;
394:   if (!viewer) PetscCall(PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes), &viewer));
396:   PetscCheckSameComm(snes, 1, viewer, 2);

398:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
399:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSTRING, &isstring));
400:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERBINARY, &isbinary));
401:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERDRAW, &isdraw));
402: #if defined(PETSC_HAVE_SAWS)
403:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERSAWS, &issaws));
404: #endif
405:   if (iascii) {
406:     SNESNormSchedule normschedule;
407:     DM               dm;
408:     PetscErrorCode (*cJ)(SNES, Vec, Mat, Mat, void *);
409:     void       *ctx;
410:     const char *pre = "";

412:     PetscCall(PetscObjectPrintClassNamePrefixType((PetscObject)snes, viewer));
413:     if (!snes->setupcalled) PetscCall(PetscViewerASCIIPrintf(viewer, "  SNES has not been set up so information may be incomplete\n"));
414:     if (snes->ops->view) {
415:       PetscCall(PetscViewerASCIIPushTab(viewer));
416:       PetscUseTypeMethod(snes, view, viewer);
417:       PetscCall(PetscViewerASCIIPopTab(viewer));
418:     }
419:     PetscCall(PetscViewerASCIIPrintf(viewer, "  maximum iterations=%" PetscInt_FMT ", maximum function evaluations=%" PetscInt_FMT "\n", snes->max_its, snes->max_funcs));
420:     PetscCall(PetscViewerASCIIPrintf(viewer, "  tolerances: relative=%g, absolute=%g, solution=%g\n", (double)snes->rtol, (double)snes->abstol, (double)snes->stol));
421:     if (snes->usesksp) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of linear solver iterations=%" PetscInt_FMT "\n", snes->linear_its));
422:     PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of function evaluations=%" PetscInt_FMT "\n", snes->nfuncs));
423:     PetscCall(SNESGetNormSchedule(snes, &normschedule));
424:     if (normschedule > 0) PetscCall(PetscViewerASCIIPrintf(viewer, "  norm schedule %s\n", SNESNormSchedules[normschedule]));
425:     if (snes->gridsequence) PetscCall(PetscViewerASCIIPrintf(viewer, "  total number of grid sequence refinements=%" PetscInt_FMT "\n", snes->gridsequence));
426:     if (snes->ksp_ewconv) {
427:       kctx = (SNESKSPEW *)snes->kspconvctx;
428:       if (kctx) {
429:         PetscCall(PetscViewerASCIIPrintf(viewer, "  Eisenstat-Walker computation of KSP relative tolerance (version %" PetscInt_FMT ")\n", kctx->version));
430:         PetscCall(PetscViewerASCIIPrintf(viewer, "    rtol_0=%g, rtol_max=%g, threshold=%g\n", (double)kctx->rtol_0, (double)kctx->rtol_max, (double)kctx->threshold));
431:         PetscCall(PetscViewerASCIIPrintf(viewer, "    gamma=%g, alpha=%g, alpha2=%g\n", (double)kctx->gamma, (double)kctx->alpha, (double)kctx->alpha2));
432:       }
433:     }
434:     if (snes->lagpreconditioner == -1) {
435:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Preconditioned is never rebuilt\n"));
436:     } else if (snes->lagpreconditioner > 1) {
437:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Preconditioned is rebuilt every %" PetscInt_FMT " new Jacobians\n", snes->lagpreconditioner));
438:     }
439:     if (snes->lagjacobian == -1) {
440:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Jacobian is never rebuilt\n"));
441:     } else if (snes->lagjacobian > 1) {
442:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Jacobian is rebuilt every %" PetscInt_FMT " SNES iterations\n", snes->lagjacobian));
443:     }
444:     PetscCall(SNESGetDM(snes, &dm));
445:     PetscCall(DMSNESGetJacobian(dm, &cJ, &ctx));
446:     if (snes->mf_operator) {
447:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Jacobian is applied matrix-free with differencing\n"));
448:       pre = "Preconditioning ";
449:     }
450:     if (cJ == SNESComputeJacobianDefault) {
451:       PetscCall(PetscViewerASCIIPrintf(viewer, "  %sJacobian is built using finite differences one column at a time\n", pre));
452:     } else if (cJ == SNESComputeJacobianDefaultColor) {
453:       PetscCall(PetscViewerASCIIPrintf(viewer, "  %sJacobian is built using finite differences with coloring\n", pre));
454:       /* it slightly breaks data encapsulation for access the DMDA information directly */
455:     } else if (cJ == SNESComputeJacobian_DMDA) {
456:       MatFDColoring fdcoloring;
457:       PetscCall(PetscObjectQuery((PetscObject)dm, "DMDASNES_FDCOLORING", (PetscObject *)&fdcoloring));
458:       if (fdcoloring) {
459:         PetscCall(PetscViewerASCIIPrintf(viewer, "  %sJacobian is built using colored finite differences on a DMDA\n", pre));
460:       } else {
461:         PetscCall(PetscViewerASCIIPrintf(viewer, "  %sJacobian is built using a DMDA local Jacobian\n", pre));
462:       }
463:     } else if (snes->mf && !snes->mf_operator) {
464:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Jacobian is applied matrix-free with differencing, no explicit Jacobian\n"));
465:     }
466:   } else if (isstring) {
467:     const char *type;
468:     PetscCall(SNESGetType(snes, &type));
469:     PetscCall(PetscViewerStringSPrintf(viewer, " SNESType: %-7.7s", type));
470:     PetscTryTypeMethod(snes, view, viewer);
471:   } else if (isbinary) {
472:     PetscInt    classid = SNES_FILE_CLASSID;
473:     MPI_Comm    comm;
474:     PetscMPIInt rank;
475:     char        type[256];

477:     PetscCall(PetscObjectGetComm((PetscObject)snes, &comm));
478:     PetscCallMPI(MPI_Comm_rank(comm, &rank));
479:     if (rank == 0) {
480:       PetscCall(PetscViewerBinaryWrite(viewer, &classid, 1, PETSC_INT));
481:       PetscCall(PetscStrncpy(type, ((PetscObject)snes)->type_name, sizeof(type)));
482:       PetscCall(PetscViewerBinaryWrite(viewer, type, sizeof(type), PETSC_CHAR));
483:     }
484:     PetscTryTypeMethod(snes, view, viewer);
485:   } else if (isdraw) {
486:     PetscDraw draw;
487:     char      str[36];
488:     PetscReal x, y, bottom, h;

490:     PetscCall(PetscViewerDrawGetDraw(viewer, 0, &draw));
491:     PetscCall(PetscDrawGetCurrentPoint(draw, &x, &y));
492:     PetscCall(PetscStrncpy(str, "SNES: ", sizeof(str)));
493:     PetscCall(PetscStrlcat(str, ((PetscObject)snes)->type_name, sizeof(str)));
494:     PetscCall(PetscDrawStringBoxed(draw, x, y, PETSC_DRAW_BLUE, PETSC_DRAW_BLACK, str, NULL, &h));
495:     bottom = y - h;
496:     PetscCall(PetscDrawPushCurrentPoint(draw, x, bottom));
497:     PetscTryTypeMethod(snes, view, viewer);
498: #if defined(PETSC_HAVE_SAWS)
499:   } else if (issaws) {
500:     PetscMPIInt rank;
501:     const char *name;

503:     PetscCall(PetscObjectGetName((PetscObject)snes, &name));
504:     PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
505:     if (!((PetscObject)snes)->amsmem && rank == 0) {
506:       char dir[1024];

508:       PetscCall(PetscObjectViewSAWs((PetscObject)snes, viewer));
509:       PetscCall(PetscSNPrintf(dir, 1024, "/PETSc/Objects/%s/its", name));
510:       PetscCallSAWs(SAWs_Register, (dir, &snes->iter, 1, SAWs_READ, SAWs_INT));
511:       if (!snes->conv_hist) PetscCall(SNESSetConvergenceHistory(snes, NULL, NULL, PETSC_DECIDE, PETSC_TRUE));
512:       PetscCall(PetscSNPrintf(dir, 1024, "/PETSc/Objects/%s/conv_hist", name));
513:       PetscCallSAWs(SAWs_Register, (dir, snes->conv_hist, 10, SAWs_READ, SAWs_DOUBLE));
514:     }
515: #endif
516:   }
517:   if (snes->linesearch) {
518:     PetscCall(SNESGetLineSearch(snes, &linesearch));
519:     PetscCall(PetscViewerASCIIPushTab(viewer));
520:     PetscCall(SNESLineSearchView(linesearch, viewer));
521:     PetscCall(PetscViewerASCIIPopTab(viewer));
522:   }
523:   if (snes->npc && snes->usesnpc) {
524:     PetscCall(PetscViewerASCIIPushTab(viewer));
525:     PetscCall(SNESView(snes->npc, viewer));
526:     PetscCall(PetscViewerASCIIPopTab(viewer));
527:   }
528:   PetscCall(PetscViewerASCIIPushTab(viewer));
529:   PetscCall(DMGetDMSNES(snes->dm, &dmsnes));
530:   PetscCall(DMSNESView(dmsnes, viewer));
531:   PetscCall(PetscViewerASCIIPopTab(viewer));
532:   if (snes->usesksp) {
533:     PetscCall(SNESGetKSP(snes, &ksp));
534:     PetscCall(PetscViewerASCIIPushTab(viewer));
535:     PetscCall(KSPView(ksp, viewer));
536:     PetscCall(PetscViewerASCIIPopTab(viewer));
537:   }
538:   if (isdraw) {
539:     PetscDraw draw;
540:     PetscCall(PetscViewerDrawGetDraw(viewer, 0, &draw));
541:     PetscCall(PetscDrawPopCurrentPoint(draw));
542:   }
543:   PetscFunctionReturn(PETSC_SUCCESS);
544: }

546: /*
547:   We retain a list of functions that also take SNES command
548:   line options. These are called at the end SNESSetFromOptions()
549: */
550: #define MAXSETFROMOPTIONS 5
551: static PetscInt numberofsetfromoptions;
552: static PetscErrorCode (*othersetfromoptions[MAXSETFROMOPTIONS])(SNES);

554: /*@C
555:   SNESAddOptionsChecker - Adds an additional function to check for `SNES` options.

557:   Not Collective

559:   Input Parameter:
560: . snescheck - function that checks for options

562:   Level: developer

564: .seealso: [](ch_snes), `SNES`, `SNESSetFromOptions()`
565: @*/
566: PetscErrorCode SNESAddOptionsChecker(PetscErrorCode (*snescheck)(SNES))
567: {
568:   PetscFunctionBegin;
569:   PetscCheck(numberofsetfromoptions < MAXSETFROMOPTIONS, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Too many options checkers, only %d allowed", MAXSETFROMOPTIONS);
570:   othersetfromoptions[numberofsetfromoptions++] = snescheck;
571:   PetscFunctionReturn(PETSC_SUCCESS);
572: }

574: static PetscErrorCode SNESSetUpMatrixFree_Private(SNES snes, PetscBool hasOperator, PetscInt version)
575: {
576:   Mat          J;
577:   MatNullSpace nullsp;

579:   PetscFunctionBegin;

582:   if (!snes->vec_func && (snes->jacobian || snes->jacobian_pre)) {
583:     Mat A = snes->jacobian, B = snes->jacobian_pre;
584:     PetscCall(MatCreateVecs(A ? A : B, NULL, &snes->vec_func));
585:   }

587:   PetscCheck(version == 1 || version == 2, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "matrix-free operator routines, only version 1 and 2");
588:   if (version == 1) {
589:     PetscCall(MatCreateSNESMF(snes, &J));
590:     PetscCall(MatMFFDSetOptionsPrefix(J, ((PetscObject)snes)->prefix));
591:     PetscCall(MatSetFromOptions(J));
592:     /* TODO: the version 2 code should be merged into the MatCreateSNESMF() and MatCreateMFFD() infrastructure and then removed */
593:   } else /* if (version == 2) */ {
594:     PetscCheck(snes->vec_func, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "SNESSetFunction() must be called first");
595: #if !defined(PETSC_USE_COMPLEX) && !defined(PETSC_USE_REAL_SINGLE) && !defined(PETSC_USE_REAL___FLOAT128) && !defined(PETSC_USE_REAL___FP16)
596:     PetscCall(MatCreateSNESMFMore(snes, snes->vec_func, &J));
597: #else
598:     SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "matrix-free operator routines (version 2)");
599: #endif
600:   }

602:   /* attach any user provided null space that was on Amat to the newly created matrix-free matrix */
603:   if (snes->jacobian) {
604:     PetscCall(MatGetNullSpace(snes->jacobian, &nullsp));
605:     if (nullsp) PetscCall(MatSetNullSpace(J, nullsp));
606:   }

608:   PetscCall(PetscInfo(snes, "Setting default matrix-free operator routines (version %" PetscInt_FMT ")\n", version));
609:   if (hasOperator) {
610:     /* This version replaces the user provided Jacobian matrix with a
611:        matrix-free version but still employs the user-provided preconditioner matrix. */
612:     PetscCall(SNESSetJacobian(snes, J, NULL, NULL, NULL));
613:   } else {
614:     /* This version replaces both the user-provided Jacobian and the user-
615:      provided preconditioner Jacobian with the default matrix-free version. */
616:     if (snes->npcside == PC_LEFT && snes->npc) {
617:       if (!snes->jacobian) PetscCall(SNESSetJacobian(snes, J, NULL, NULL, NULL));
618:     } else {
619:       KSP       ksp;
620:       PC        pc;
621:       PetscBool match;

623:       PetscCall(SNESSetJacobian(snes, J, J, MatMFFDComputeJacobian, NULL));
624:       /* Force no preconditioner */
625:       PetscCall(SNESGetKSP(snes, &ksp));
626:       PetscCall(KSPGetPC(ksp, &pc));
627:       PetscCall(PetscObjectTypeCompareAny((PetscObject)pc, &match, PCSHELL, PCH2OPUS, ""));
628:       if (!match) {
629:         PetscCall(PetscInfo(snes, "Setting default matrix-free preconditioner routines\nThat is no preconditioner is being used\n"));
630:         PetscCall(PCSetType(pc, PCNONE));
631:       }
632:     }
633:   }
634:   PetscCall(MatDestroy(&J));
635:   PetscFunctionReturn(PETSC_SUCCESS);
636: }

638: static PetscErrorCode DMRestrictHook_SNESVecSol(DM dmfine, Mat Restrict, Vec Rscale, Mat Inject, DM dmcoarse, void *ctx)
639: {
640:   SNES snes = (SNES)ctx;
641:   Vec  Xfine, Xfine_named = NULL, Xcoarse;

643:   PetscFunctionBegin;
644:   if (PetscLogPrintInfo) {
645:     PetscInt finelevel, coarselevel, fineclevel, coarseclevel;
646:     PetscCall(DMGetRefineLevel(dmfine, &finelevel));
647:     PetscCall(DMGetCoarsenLevel(dmfine, &fineclevel));
648:     PetscCall(DMGetRefineLevel(dmcoarse, &coarselevel));
649:     PetscCall(DMGetCoarsenLevel(dmcoarse, &coarseclevel));
650:     PetscCall(PetscInfo(dmfine, "Restricting SNES solution vector from level %" PetscInt_FMT "-%" PetscInt_FMT " to level %" PetscInt_FMT "-%" PetscInt_FMT "\n", finelevel, fineclevel, coarselevel, coarseclevel));
651:   }
652:   if (dmfine == snes->dm) Xfine = snes->vec_sol;
653:   else {
654:     PetscCall(DMGetNamedGlobalVector(dmfine, "SNESVecSol", &Xfine_named));
655:     Xfine = Xfine_named;
656:   }
657:   PetscCall(DMGetNamedGlobalVector(dmcoarse, "SNESVecSol", &Xcoarse));
658:   if (Inject) {
659:     PetscCall(MatRestrict(Inject, Xfine, Xcoarse));
660:   } else {
661:     PetscCall(MatRestrict(Restrict, Xfine, Xcoarse));
662:     PetscCall(VecPointwiseMult(Xcoarse, Xcoarse, Rscale));
663:   }
664:   PetscCall(DMRestoreNamedGlobalVector(dmcoarse, "SNESVecSol", &Xcoarse));
665:   if (Xfine_named) PetscCall(DMRestoreNamedGlobalVector(dmfine, "SNESVecSol", &Xfine_named));
666:   PetscFunctionReturn(PETSC_SUCCESS);
667: }

669: static PetscErrorCode DMCoarsenHook_SNESVecSol(DM dm, DM dmc, void *ctx)
670: {
671:   PetscFunctionBegin;
672:   PetscCall(DMCoarsenHookAdd(dmc, DMCoarsenHook_SNESVecSol, DMRestrictHook_SNESVecSol, ctx));
673:   PetscFunctionReturn(PETSC_SUCCESS);
674: }

676: /* This may be called to rediscretize the operator on levels of linear multigrid. The DM shuffle is so the user can
677:  * safely call SNESGetDM() in their residual evaluation routine. */
678: static PetscErrorCode KSPComputeOperators_SNES(KSP ksp, Mat A, Mat B, void *ctx)
679: {
680:   SNES  snes = (SNES)ctx;
681:   Vec   X, Xnamed = NULL;
682:   DM    dmsave;
683:   void *ctxsave;
684:   PetscErrorCode (*jac)(SNES, Vec, Mat, Mat, void *) = NULL;

686:   PetscFunctionBegin;
687:   dmsave = snes->dm;
688:   PetscCall(KSPGetDM(ksp, &snes->dm));
689:   if (dmsave == snes->dm) X = snes->vec_sol; /* We are on the finest level */
690:   else { /* We are on a coarser level, this vec was initialized using a DM restrict hook */ PetscCall(DMGetNamedGlobalVector(snes->dm, "SNESVecSol", &Xnamed));
691:     X = Xnamed;
692:     PetscCall(SNESGetJacobian(snes, NULL, NULL, &jac, &ctxsave));
693:     /* If the DM's don't match up, the MatFDColoring context needed for the jacobian won't match up either -- fixit. */
694:     if (jac == SNESComputeJacobianDefaultColor) PetscCall(SNESSetJacobian(snes, NULL, NULL, SNESComputeJacobianDefaultColor, NULL));
695:   }
696:   /* Make sure KSP DM has the Jacobian computation routine */
697:   {
698:     DMSNES sdm;

700:     PetscCall(DMGetDMSNES(snes->dm, &sdm));
701:     if (!sdm->ops->computejacobian) PetscCall(DMCopyDMSNES(dmsave, snes->dm));
702:   }
703:   /* Compute the operators */
704:   PetscCall(SNESComputeJacobian(snes, X, A, B));
705:   /* Put the previous context back */
706:   if (snes->dm != dmsave && jac == SNESComputeJacobianDefaultColor) PetscCall(SNESSetJacobian(snes, NULL, NULL, jac, ctxsave));

708:   if (Xnamed) PetscCall(DMRestoreNamedGlobalVector(snes->dm, "SNESVecSol", &Xnamed));
709:   snes->dm = dmsave;
710:   PetscFunctionReturn(PETSC_SUCCESS);
711: }

713: /*@
714:   SNESSetUpMatrices - ensures that matrices are available for `SNES` Newton-like methods, this is called by `SNESSetUp_XXX()`

716:   Collective

718:   Input Parameter:
719: . snes - `SNES` object to configure

721:   Level: developer

723:   Note:
724:   If the matrices do not yet exist it attempts to create them based on options previously set for the `SNES` such as `-snes_mf`

726: .seealso: [](ch_snes), `SNES`, `SNESSetUp()`
727: @*/
728: PetscErrorCode SNESSetUpMatrices(SNES snes)
729: {
730:   DM     dm;
731:   DMSNES sdm;

733:   PetscFunctionBegin;
734:   PetscCall(SNESGetDM(snes, &dm));
735:   PetscCall(DMGetDMSNES(dm, &sdm));
736:   if (!snes->jacobian && snes->mf) {
737:     Mat   J;
738:     void *functx;
739:     PetscCall(MatCreateSNESMF(snes, &J));
740:     PetscCall(MatMFFDSetOptionsPrefix(J, ((PetscObject)snes)->prefix));
741:     PetscCall(MatSetFromOptions(J));
742:     PetscCall(SNESGetFunction(snes, NULL, NULL, &functx));
743:     PetscCall(SNESSetJacobian(snes, J, J, NULL, NULL));
744:     PetscCall(MatDestroy(&J));
745:   } else if (snes->mf_operator && !snes->jacobian_pre && !snes->jacobian) {
746:     Mat J, B;
747:     PetscCall(MatCreateSNESMF(snes, &J));
748:     PetscCall(MatMFFDSetOptionsPrefix(J, ((PetscObject)snes)->prefix));
749:     PetscCall(MatSetFromOptions(J));
750:     PetscCall(DMCreateMatrix(snes->dm, &B));
751:     /* sdm->computejacobian was already set to reach here */
752:     PetscCall(SNESSetJacobian(snes, J, B, NULL, NULL));
753:     PetscCall(MatDestroy(&J));
754:     PetscCall(MatDestroy(&B));
755:   } else if (!snes->jacobian_pre) {
756:     PetscDS   prob;
757:     Mat       J, B;
758:     PetscBool hasPrec = PETSC_FALSE;

760:     J = snes->jacobian;
761:     PetscCall(DMGetDS(dm, &prob));
762:     if (prob) PetscCall(PetscDSHasJacobianPreconditioner(prob, &hasPrec));
763:     if (J) PetscCall(PetscObjectReference((PetscObject)J));
764:     else if (hasPrec) PetscCall(DMCreateMatrix(snes->dm, &J));
765:     PetscCall(DMCreateMatrix(snes->dm, &B));
766:     PetscCall(SNESSetJacobian(snes, J ? J : B, B, NULL, NULL));
767:     PetscCall(MatDestroy(&J));
768:     PetscCall(MatDestroy(&B));
769:   }
770:   {
771:     KSP ksp;
772:     PetscCall(SNESGetKSP(snes, &ksp));
773:     PetscCall(KSPSetComputeOperators(ksp, KSPComputeOperators_SNES, snes));
774:     PetscCall(DMCoarsenHookAdd(snes->dm, DMCoarsenHook_SNESVecSol, DMRestrictHook_SNESVecSol, snes));
775:   }
776:   PetscFunctionReturn(PETSC_SUCCESS);
777: }

779: static PetscErrorCode SNESMonitorPauseFinal_Internal(SNES snes)
780: {
781:   PetscInt i;

783:   PetscFunctionBegin;
784:   if (!snes->pauseFinal) PetscFunctionReturn(PETSC_SUCCESS);
785:   for (i = 0; i < snes->numbermonitors; ++i) {
786:     PetscViewerAndFormat *vf = (PetscViewerAndFormat *)snes->monitorcontext[i];
787:     PetscDraw             draw;
788:     PetscReal             lpause;

790:     if (!vf) continue;
791:     if (vf->lg) {
792:       if (!PetscCheckPointer(vf->lg, PETSC_OBJECT)) continue;
793:       if (((PetscObject)vf->lg)->classid != PETSC_DRAWLG_CLASSID) continue;
794:       PetscCall(PetscDrawLGGetDraw(vf->lg, &draw));
795:       PetscCall(PetscDrawGetPause(draw, &lpause));
796:       PetscCall(PetscDrawSetPause(draw, -1.0));
797:       PetscCall(PetscDrawPause(draw));
798:       PetscCall(PetscDrawSetPause(draw, lpause));
799:     } else {
800:       PetscBool isdraw;

802:       if (!PetscCheckPointer(vf->viewer, PETSC_OBJECT)) continue;
803:       if (((PetscObject)vf->viewer)->classid != PETSC_VIEWER_CLASSID) continue;
804:       PetscCall(PetscObjectTypeCompare((PetscObject)vf->viewer, PETSCVIEWERDRAW, &isdraw));
805:       if (!isdraw) continue;
806:       PetscCall(PetscViewerDrawGetDraw(vf->viewer, 0, &draw));
807:       PetscCall(PetscDrawGetPause(draw, &lpause));
808:       PetscCall(PetscDrawSetPause(draw, -1.0));
809:       PetscCall(PetscDrawPause(draw));
810:       PetscCall(PetscDrawSetPause(draw, lpause));
811:     }
812:   }
813:   PetscFunctionReturn(PETSC_SUCCESS);
814: }

816: /*@C
817:   SNESMonitorSetFromOptions - Sets a monitor function and viewer appropriate for the type indicated by the user

819:   Collective

821:   Input Parameters:
822: + snes         - `SNES` object you wish to monitor
823: . name         - the monitor type one is seeking
824: . help         - message indicating what monitoring is done
825: . manual       - manual page for the monitor
826: . monitor      - the monitor function
827: - monitorsetup - a function that is called once ONLY if the user selected this monitor that may set additional features of the `SNES` or `PetscViewer` objects

829:   Options Database Key:
830: . -name - trigger the use of this monitor in `SNESSetFromOptions()`

832:   Level: advanced

834: .seealso: [](ch_snes), `PetscOptionsGetViewer()`, `PetscOptionsGetReal()`, `PetscOptionsHasName()`, `PetscOptionsGetString()`,
835:           `PetscOptionsGetIntArray()`, `PetscOptionsGetRealArray()`, `PetscOptionsBool()`
836:           `PetscOptionsInt()`, `PetscOptionsString()`, `PetscOptionsReal()`,
837:           `PetscOptionsName()`, `PetscOptionsBegin()`, `PetscOptionsEnd()`, `PetscOptionsHeadBegin()`,
838:           `PetscOptionsStringArray()`, `PetscOptionsRealArray()`, `PetscOptionsScalar()`,
839:           `PetscOptionsBoolGroupBegin()`, `PetscOptionsBoolGroup()`, `PetscOptionsBoolGroupEnd()`,
840:           `PetscOptionsFList()`, `PetscOptionsEList()`
841: @*/
842: PetscErrorCode SNESMonitorSetFromOptions(SNES snes, const char name[], const char help[], const char manual[], PetscErrorCode (*monitor)(SNES, PetscInt, PetscReal, PetscViewerAndFormat *), PetscErrorCode (*monitorsetup)(SNES, PetscViewerAndFormat *))
843: {
844:   PetscViewer       viewer;
845:   PetscViewerFormat format;
846:   PetscBool         flg;

848:   PetscFunctionBegin;
849:   PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, name, &viewer, &format, &flg));
850:   if (flg) {
851:     PetscViewerAndFormat *vf;
852:     PetscCall(PetscViewerAndFormatCreate(viewer, format, &vf));
853:     PetscCall(PetscObjectDereference((PetscObject)viewer));
854:     if (monitorsetup) PetscCall((*monitorsetup)(snes, vf));
855:     PetscCall(SNESMonitorSet(snes, (PetscErrorCode(*)(SNES, PetscInt, PetscReal, void *))monitor, vf, (PetscErrorCode(*)(void **))PetscViewerAndFormatDestroy));
856:   }
857:   PetscFunctionReturn(PETSC_SUCCESS);
858: }

860: PetscErrorCode SNESEWSetFromOptions_Private(SNESKSPEW *kctx, PetscBool print_api, MPI_Comm comm, const char *prefix)
861: {
862:   const char *api = print_api ? "SNESKSPSetParametersEW" : NULL;

864:   PetscFunctionBegin;
865:   PetscOptionsBegin(comm, prefix, "Eisenstat and Walker type forcing options", "KSP");
866:   PetscCall(PetscOptionsInt("-ksp_ew_version", "Version 1, 2 or 3", api, kctx->version, &kctx->version, NULL));
867:   PetscCall(PetscOptionsReal("-ksp_ew_rtol0", "0 <= rtol0 < 1", api, kctx->rtol_0, &kctx->rtol_0, NULL));
868:   kctx->rtol_max = PetscMax(kctx->rtol_0, kctx->rtol_max);
869:   PetscCall(PetscOptionsReal("-ksp_ew_rtolmax", "0 <= rtolmax < 1", api, kctx->rtol_max, &kctx->rtol_max, NULL));
870:   PetscCall(PetscOptionsReal("-ksp_ew_gamma", "0 <= gamma <= 1", api, kctx->gamma, &kctx->gamma, NULL));
871:   PetscCall(PetscOptionsReal("-ksp_ew_alpha", "1 < alpha <= 2", api, kctx->alpha, &kctx->alpha, NULL));
872:   PetscCall(PetscOptionsReal("-ksp_ew_alpha2", "alpha2", NULL, kctx->alpha2, &kctx->alpha2, NULL));
873:   PetscCall(PetscOptionsReal("-ksp_ew_threshold", "0 < threshold < 1", api, kctx->threshold, &kctx->threshold, NULL));
874:   PetscCall(PetscOptionsReal("-ksp_ew_v4_p1", "p1", NULL, kctx->v4_p1, &kctx->v4_p1, NULL));
875:   PetscCall(PetscOptionsReal("-ksp_ew_v4_p2", "p2", NULL, kctx->v4_p2, &kctx->v4_p2, NULL));
876:   PetscCall(PetscOptionsReal("-ksp_ew_v4_p3", "p3", NULL, kctx->v4_p3, &kctx->v4_p3, NULL));
877:   PetscCall(PetscOptionsReal("-ksp_ew_v4_m1", "Scaling when rk-1 in [p2,p3)", NULL, kctx->v4_m1, &kctx->v4_m1, NULL));
878:   PetscCall(PetscOptionsReal("-ksp_ew_v4_m2", "Scaling when rk-1 in [p3,+infty)", NULL, kctx->v4_m2, &kctx->v4_m2, NULL));
879:   PetscCall(PetscOptionsReal("-ksp_ew_v4_m3", "Threshold for successive rtol (0.1 in Eq.7)", NULL, kctx->v4_m3, &kctx->v4_m3, NULL));
880:   PetscCall(PetscOptionsReal("-ksp_ew_v4_m4", "Adaptation scaling (0.5 in Eq.7)", NULL, kctx->v4_m4, &kctx->v4_m4, NULL));
881:   PetscOptionsEnd();
882:   PetscFunctionReturn(PETSC_SUCCESS);
883: }

885: /*@
886:   SNESSetFromOptions - Sets various `SNES` and `KSP` parameters from user options.

888:   Collective

890:   Input Parameter:
891: . snes - the `SNES` context

893:   Options Database Keys:
894: + -snes_type <type>                                                            - newtonls, newtontr, ngmres, ncg, nrichardson, qn, vi, fas, `SNESType` for complete list
895: . -snes_stol <stol>                                                            - convergence tolerance in terms of the norm of the change in the solution between steps
896: . -snes_atol <abstol>                                                          - absolute tolerance of residual norm
897: . -snes_rtol <rtol>                                                            - relative decrease in tolerance norm from initial
898: . -snes_divergence_tolerance <divtol>                                          - if the residual goes above divtol*rnorm0, exit with divergence
899: . -snes_force_iteration <force>                                                - force `SNESSolve()` to take at least one iteration
900: . -snes_max_it <max_it>                                                        - maximum number of iterations
901: . -snes_max_funcs <max_funcs>                                                  - maximum number of function evaluations
902: . -snes_max_fail <max_fail>                                                    - maximum number of line search failures allowed before stopping, default is none
903: . -snes_max_linear_solve_fail                                                  - number of linear solver failures before SNESSolve() stops
904: . -snes_lag_preconditioner <lag>                                               - how often preconditioner is rebuilt (use -1 to never rebuild)
905: . -snes_lag_preconditioner_persists <true,false>                               - retains the -snes_lag_preconditioner information across multiple SNESSolve()
906: . -snes_lag_jacobian <lag>                                                     - how often Jacobian is rebuilt (use -1 to never rebuild)
907: . -snes_lag_jacobian_persists <true,false>                                     - retains the -snes_lag_jacobian information across multiple SNESSolve()
908: . -snes_tr_tol <trtol>                                                         - trust region tolerance
909: . -snes_convergence_test <default,skip,correct_pressure>                       - convergence test in nonlinear solver. default `SNESConvergedDefault()`. skip `SNESConvergedSkip()` means continue iterating until max_it or some other criterion is reached, saving expense of convergence test. correct_pressure `SNESConvergedCorrectPressure()` has special handling of a pressure null space.
910: . -snes_monitor [ascii][:filename][:viewer format]                             - prints residual norm at each iteration. if no filename given prints to stdout
911: . -snes_monitor_solution [ascii binary draw][:filename][:viewer format]        - plots solution at each iteration
912: . -snes_monitor_residual [ascii binary draw][:filename][:viewer format]        - plots residual (not its norm) at each iteration
913: . -snes_monitor_solution_update [ascii binary draw][:filename][:viewer format] - plots update to solution at each iteration
914: . -snes_monitor_lg_residualnorm                                                - plots residual norm at each iteration
915: . -snes_monitor_lg_range                                                       - plots residual norm at each iteration
916: . -snes_monitor_pause_final                                                    - Pauses all monitor drawing after the solver ends
917: . -snes_fd                                                                     - use finite differences to compute Jacobian; very slow, only for testing
918: . -snes_fd_color                                                               - use finite differences with coloring to compute Jacobian
919: . -snes_mf_ksp_monitor                                                         - if using matrix-free multiply then print h at each `KSP` iteration
920: . -snes_converged_reason                                                       - print the reason for convergence/divergence after each solve
921: . -npc_snes_type <type>                                                        - the `SNES` type to use as a nonlinear preconditioner
922: . -snes_test_jacobian <optional threshold>                                     - compare the user provided Jacobian with one computed via finite differences to check for errors.  If a threshold is given, display only those entries whose difference is greater than the threshold.
923: - -snes_test_jacobian_view                                                     - display the user provided Jacobian, the finite difference Jacobian and the difference between them to help users detect the location of errors in the user provided Jacobian.

925:   Options Database Keys for Eisenstat-Walker method:
926: + -snes_ksp_ew                       - use Eisenstat-Walker method for determining linear system convergence
927: . -snes_ksp_ew_version ver           - version of  Eisenstat-Walker method
928: . -snes_ksp_ew_rtol0 <rtol0>         - Sets rtol0
929: . -snes_ksp_ew_rtolmax <rtolmax>     - Sets rtolmax
930: . -snes_ksp_ew_gamma <gamma>         - Sets gamma
931: . -snes_ksp_ew_alpha <alpha>         - Sets alpha
932: . -snes_ksp_ew_alpha2 <alpha2>       - Sets alpha2
933: - -snes_ksp_ew_threshold <threshold> - Sets threshold

935:   Level: beginner

937:   Notes:
938:   To see all options, run your program with the -help option or consult the users manual

940:   `SNES` supports three approaches for computing (approximate) Jacobians: user provided via `SNESSetJacobian()`, matrix-free, and computing explicitly with
941:   finite differences and coloring using `MatFDColoring`. It is also possible to use automatic differentiation and the `MatFDColoring` object.

943: .seealso: [](ch_snes), `SNESType`, `SNESSetOptionsPrefix()`, `SNESResetFromOptions()`, `SNES`, `SNESCreate()`
944: @*/
945: PetscErrorCode SNESSetFromOptions(SNES snes)
946: {
947:   PetscBool   flg, pcset, persist, set;
948:   PetscInt    i, indx, lag, grids;
949:   const char *deft        = SNESNEWTONLS;
950:   const char *convtests[] = {"default", "skip", "correct_pressure"};
951:   SNESKSPEW  *kctx        = NULL;
952:   char        type[256], monfilename[PETSC_MAX_PATH_LEN], ewprefix[256];
953:   PCSide      pcside;
954:   const char *optionsprefix;

956:   PetscFunctionBegin;
958:   PetscCall(SNESRegisterAll());
959:   PetscObjectOptionsBegin((PetscObject)snes);
960:   if (((PetscObject)snes)->type_name) deft = ((PetscObject)snes)->type_name;
961:   PetscCall(PetscOptionsFList("-snes_type", "Nonlinear solver method", "SNESSetType", SNESList, deft, type, 256, &flg));
962:   if (flg) {
963:     PetscCall(SNESSetType(snes, type));
964:   } else if (!((PetscObject)snes)->type_name) {
965:     PetscCall(SNESSetType(snes, deft));
966:   }
967:   PetscCall(PetscOptionsReal("-snes_stol", "Stop if step length less than", "SNESSetTolerances", snes->stol, &snes->stol, NULL));
968:   PetscCall(PetscOptionsReal("-snes_atol", "Stop if function norm less than", "SNESSetTolerances", snes->abstol, &snes->abstol, NULL));

970:   PetscCall(PetscOptionsReal("-snes_rtol", "Stop if decrease in function norm less than", "SNESSetTolerances", snes->rtol, &snes->rtol, NULL));
971:   PetscCall(PetscOptionsReal("-snes_divergence_tolerance", "Stop if residual norm increases by this factor", "SNESSetDivergenceTolerance", snes->divtol, &snes->divtol, NULL));
972:   PetscCall(PetscOptionsInt("-snes_max_it", "Maximum iterations", "SNESSetTolerances", snes->max_its, &snes->max_its, NULL));
973:   PetscCall(PetscOptionsInt("-snes_max_funcs", "Maximum function evaluations", "SNESSetTolerances", snes->max_funcs, &snes->max_funcs, NULL));
974:   PetscCall(PetscOptionsInt("-snes_max_fail", "Maximum nonlinear step failures", "SNESSetMaxNonlinearStepFailures", snes->maxFailures, &snes->maxFailures, NULL));
975:   PetscCall(PetscOptionsInt("-snes_max_linear_solve_fail", "Maximum failures in linear solves allowed", "SNESSetMaxLinearSolveFailures", snes->maxLinearSolveFailures, &snes->maxLinearSolveFailures, NULL));
976:   PetscCall(PetscOptionsBool("-snes_error_if_not_converged", "Generate error if solver does not converge", "SNESSetErrorIfNotConverged", snes->errorifnotconverged, &snes->errorifnotconverged, NULL));
977:   PetscCall(PetscOptionsBool("-snes_force_iteration", "Force SNESSolve() to take at least one iteration", "SNESSetForceIteration", snes->forceiteration, &snes->forceiteration, NULL));
978:   PetscCall(PetscOptionsBool("-snes_check_jacobian_domain_error", "Check Jacobian domain error after Jacobian evaluation", "SNESCheckJacobianDomainError", snes->checkjacdomainerror, &snes->checkjacdomainerror, NULL));

980:   PetscCall(PetscOptionsInt("-snes_lag_preconditioner", "How often to rebuild preconditioner", "SNESSetLagPreconditioner", snes->lagpreconditioner, &lag, &flg));
981:   if (flg) {
982:     PetscCheck(lag != -1, PetscObjectComm((PetscObject)snes), PETSC_ERR_USER, "Cannot set the lag to -1 from the command line since the preconditioner must be built as least once, perhaps you mean -2");
983:     PetscCall(SNESSetLagPreconditioner(snes, lag));
984:   }
985:   PetscCall(PetscOptionsBool("-snes_lag_preconditioner_persists", "Preconditioner lagging through multiple SNES solves", "SNESSetLagPreconditionerPersists", snes->lagjac_persist, &persist, &flg));
986:   if (flg) PetscCall(SNESSetLagPreconditionerPersists(snes, persist));
987:   PetscCall(PetscOptionsInt("-snes_lag_jacobian", "How often to rebuild Jacobian", "SNESSetLagJacobian", snes->lagjacobian, &lag, &flg));
988:   if (flg) {
989:     PetscCheck(lag != -1, PetscObjectComm((PetscObject)snes), PETSC_ERR_USER, "Cannot set the lag to -1 from the command line since the Jacobian must be built as least once, perhaps you mean -2");
990:     PetscCall(SNESSetLagJacobian(snes, lag));
991:   }
992:   PetscCall(PetscOptionsBool("-snes_lag_jacobian_persists", "Jacobian lagging through multiple SNES solves", "SNESSetLagJacobianPersists", snes->lagjac_persist, &persist, &flg));
993:   if (flg) PetscCall(SNESSetLagJacobianPersists(snes, persist));

995:   PetscCall(PetscOptionsInt("-snes_grid_sequence", "Use grid sequencing to generate initial guess", "SNESSetGridSequence", snes->gridsequence, &grids, &flg));
996:   if (flg) PetscCall(SNESSetGridSequence(snes, grids));

998:   PetscCall(PetscOptionsEList("-snes_convergence_test", "Convergence test", "SNESSetConvergenceTest", convtests, PETSC_STATIC_ARRAY_LENGTH(convtests), "default", &indx, &flg));
999:   if (flg) {
1000:     switch (indx) {
1001:     case 0:
1002:       PetscCall(SNESSetConvergenceTest(snes, SNESConvergedDefault, NULL, NULL));
1003:       break;
1004:     case 1:
1005:       PetscCall(SNESSetConvergenceTest(snes, SNESConvergedSkip, NULL, NULL));
1006:       break;
1007:     case 2:
1008:       PetscCall(SNESSetConvergenceTest(snes, SNESConvergedCorrectPressure, NULL, NULL));
1009:       break;
1010:     }
1011:   }

1013:   PetscCall(PetscOptionsEList("-snes_norm_schedule", "SNES Norm schedule", "SNESSetNormSchedule", SNESNormSchedules, 5, "function", &indx, &flg));
1014:   if (flg) PetscCall(SNESSetNormSchedule(snes, (SNESNormSchedule)indx));

1016:   PetscCall(PetscOptionsEList("-snes_function_type", "SNES Norm schedule", "SNESSetFunctionType", SNESFunctionTypes, 2, "unpreconditioned", &indx, &flg));
1017:   if (flg) PetscCall(SNESSetFunctionType(snes, (SNESFunctionType)indx));

1019:   kctx = (SNESKSPEW *)snes->kspconvctx;

1021:   PetscCall(PetscOptionsBool("-snes_ksp_ew", "Use Eisentat-Walker linear system convergence test", "SNESKSPSetUseEW", snes->ksp_ewconv, &snes->ksp_ewconv, NULL));

1023:   PetscCall(SNESGetOptionsPrefix(snes, &optionsprefix));
1024:   PetscCall(PetscSNPrintf(ewprefix, sizeof(ewprefix), "%s%s", optionsprefix ? optionsprefix : "", "snes_"));
1025:   PetscCall(SNESEWSetFromOptions_Private(kctx, PETSC_TRUE, PetscObjectComm((PetscObject)snes), ewprefix));

1027:   flg = PETSC_FALSE;
1028:   PetscCall(PetscOptionsBool("-snes_monitor_cancel", "Remove all monitors", "SNESMonitorCancel", flg, &flg, &set));
1029:   if (set && flg) PetscCall(SNESMonitorCancel(snes));

1031:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor", "Monitor norm of function", "SNESMonitorDefault", SNESMonitorDefault, SNESMonitorDefaultSetUp));
1032:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_short", "Monitor norm of function with fewer digits", "SNESMonitorDefaultShort", SNESMonitorDefaultShort, NULL));
1033:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_range", "Monitor range of elements of function", "SNESMonitorRange", SNESMonitorRange, NULL));

1035:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_ratio", "Monitor ratios of the norm of function for consecutive steps", "SNESMonitorRatio", SNESMonitorRatio, SNESMonitorRatioSetUp));
1036:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_field", "Monitor norm of function (split into fields)", "SNESMonitorDefaultField", SNESMonitorDefaultField, NULL));
1037:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_solution", "View solution at each iteration", "SNESMonitorSolution", SNESMonitorSolution, NULL));
1038:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_solution_update", "View correction at each iteration", "SNESMonitorSolutionUpdate", SNESMonitorSolutionUpdate, NULL));
1039:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_residual", "View residual at each iteration", "SNESMonitorResidual", SNESMonitorResidual, NULL));
1040:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_jacupdate_spectrum", "Print the change in the spectrum of the Jacobian", "SNESMonitorJacUpdateSpectrum", SNESMonitorJacUpdateSpectrum, NULL));
1041:   PetscCall(SNESMonitorSetFromOptions(snes, "-snes_monitor_fields", "Monitor norm of function per field", "SNESMonitorSet", SNESMonitorFields, NULL));
1042:   PetscCall(PetscOptionsBool("-snes_monitor_pause_final", "Pauses all draw monitors at the final iterate", "SNESMonitorPauseFinal_Internal", PETSC_FALSE, &snes->pauseFinal, NULL));

1044:   PetscCall(PetscOptionsString("-snes_monitor_python", "Use Python function", "SNESMonitorSet", NULL, monfilename, sizeof(monfilename), &flg));
1045:   if (flg) PetscCall(PetscPythonMonitorSet((PetscObject)snes, monfilename));

1047:   flg = PETSC_FALSE;
1048:   PetscCall(PetscOptionsBool("-snes_monitor_lg_range", "Plot function range at each iteration", "SNESMonitorLGRange", flg, &flg, NULL));
1049:   if (flg) {
1050:     PetscViewer ctx;

1052:     PetscCall(PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes), NULL, NULL, PETSC_DECIDE, PETSC_DECIDE, 400, 300, &ctx));
1053:     PetscCall(SNESMonitorSet(snes, SNESMonitorLGRange, ctx, (PetscErrorCode(*)(void **))PetscViewerDestroy));
1054:   }

1056:   flg = PETSC_FALSE;
1057:   PetscCall(PetscOptionsBool("-snes_converged_reason_view_cancel", "Remove all converged reason viewers", "SNESConvergedReasonViewCancel", flg, &flg, &set));
1058:   if (set && flg) PetscCall(SNESConvergedReasonViewCancel(snes));

1060:   flg = PETSC_FALSE;
1061:   PetscCall(PetscOptionsBool("-snes_fd", "Use finite differences (slow) to compute Jacobian", "SNESComputeJacobianDefault", flg, &flg, NULL));
1062:   if (flg) {
1063:     void *functx;
1064:     DM    dm;
1065:     PetscCall(SNESGetDM(snes, &dm));
1066:     PetscCall(DMSNESUnsetJacobianContext_Internal(dm));
1067:     PetscCall(SNESGetFunction(snes, NULL, NULL, &functx));
1068:     PetscCall(SNESSetJacobian(snes, snes->jacobian, snes->jacobian_pre, SNESComputeJacobianDefault, functx));
1069:     PetscCall(PetscInfo(snes, "Setting default finite difference Jacobian matrix\n"));
1070:   }

1072:   flg = PETSC_FALSE;
1073:   PetscCall(PetscOptionsBool("-snes_fd_function", "Use finite differences (slow) to compute function from user objective", "SNESObjectiveComputeFunctionDefaultFD", flg, &flg, NULL));
1074:   if (flg) PetscCall(SNESSetFunction(snes, NULL, SNESObjectiveComputeFunctionDefaultFD, NULL));

1076:   flg = PETSC_FALSE;
1077:   PetscCall(PetscOptionsBool("-snes_fd_color", "Use finite differences with coloring to compute Jacobian", "SNESComputeJacobianDefaultColor", flg, &flg, NULL));
1078:   if (flg) {
1079:     DM dm;
1080:     PetscCall(SNESGetDM(snes, &dm));
1081:     PetscCall(DMSNESUnsetJacobianContext_Internal(dm));
1082:     PetscCall(SNESSetJacobian(snes, snes->jacobian, snes->jacobian_pre, SNESComputeJacobianDefaultColor, NULL));
1083:     PetscCall(PetscInfo(snes, "Setting default finite difference coloring Jacobian matrix\n"));
1084:   }

1086:   flg = PETSC_FALSE;
1087:   PetscCall(PetscOptionsBool("-snes_mf_operator", "Use a Matrix-Free Jacobian with user-provided preconditioner matrix", "SNESSetUseMatrixFree", PETSC_FALSE, &snes->mf_operator, &flg));
1088:   if (flg && snes->mf_operator) {
1089:     snes->mf_operator = PETSC_TRUE;
1090:     snes->mf          = PETSC_TRUE;
1091:   }
1092:   flg = PETSC_FALSE;
1093:   PetscCall(PetscOptionsBool("-snes_mf", "Use a Matrix-Free Jacobian with no preconditioner matrix", "SNESSetUseMatrixFree", PETSC_FALSE, &snes->mf, &flg));
1094:   if (!flg && snes->mf_operator) snes->mf = PETSC_TRUE;
1095:   PetscCall(PetscOptionsInt("-snes_mf_version", "Matrix-Free routines version 1 or 2", "None", snes->mf_version, &snes->mf_version, NULL));

1097:   flg = PETSC_FALSE;
1098:   PetscCall(SNESGetNPCSide(snes, &pcside));
1099:   PetscCall(PetscOptionsEnum("-snes_npc_side", "SNES nonlinear preconditioner side", "SNESSetNPCSide", PCSides, (PetscEnum)pcside, (PetscEnum *)&pcside, &flg));
1100:   if (flg) PetscCall(SNESSetNPCSide(snes, pcside));

1102: #if defined(PETSC_HAVE_SAWS)
1103:   /*
1104:     Publish convergence information using SAWs
1105:   */
1106:   flg = PETSC_FALSE;
1107:   PetscCall(PetscOptionsBool("-snes_monitor_saws", "Publish SNES progress using SAWs", "SNESMonitorSet", flg, &flg, NULL));
1108:   if (flg) {
1109:     void *ctx;
1110:     PetscCall(SNESMonitorSAWsCreate(snes, &ctx));
1111:     PetscCall(SNESMonitorSet(snes, SNESMonitorSAWs, ctx, SNESMonitorSAWsDestroy));
1112:   }
1113: #endif
1114: #if defined(PETSC_HAVE_SAWS)
1115:   {
1116:     PetscBool set;
1117:     flg = PETSC_FALSE;
1118:     PetscCall(PetscOptionsBool("-snes_saws_block", "Block for SAWs at end of SNESSolve", "PetscObjectSAWsBlock", ((PetscObject)snes)->amspublishblock, &flg, &set));
1119:     if (set) PetscCall(PetscObjectSAWsSetBlock((PetscObject)snes, flg));
1120:   }
1121: #endif

1123:   for (i = 0; i < numberofsetfromoptions; i++) PetscCall((*othersetfromoptions[i])(snes));

1125:   PetscTryTypeMethod(snes, setfromoptions, PetscOptionsObject);

1127:   /* process any options handlers added with PetscObjectAddOptionsHandler() */
1128:   PetscCall(PetscObjectProcessOptionsHandlers((PetscObject)snes, PetscOptionsObject));
1129:   PetscOptionsEnd();

1131:   if (snes->linesearch) {
1132:     PetscCall(SNESGetLineSearch(snes, &snes->linesearch));
1133:     PetscCall(SNESLineSearchSetFromOptions(snes->linesearch));
1134:   }

1136:   if (snes->usesksp) {
1137:     if (!snes->ksp) PetscCall(SNESGetKSP(snes, &snes->ksp));
1138:     PetscCall(KSPSetOperators(snes->ksp, snes->jacobian, snes->jacobian_pre));
1139:     PetscCall(KSPSetFromOptions(snes->ksp));
1140:   }

1142:   /* if user has set the SNES NPC type via options database, create it. */
1143:   PetscCall(SNESGetOptionsPrefix(snes, &optionsprefix));
1144:   PetscCall(PetscOptionsHasName(((PetscObject)snes)->options, optionsprefix, "-npc_snes_type", &pcset));
1145:   if (pcset && (!snes->npc)) PetscCall(SNESGetNPC(snes, &snes->npc));
1146:   if (snes->npc) PetscCall(SNESSetFromOptions(snes->npc));
1147:   snes->setfromoptionscalled++;
1148:   PetscFunctionReturn(PETSC_SUCCESS);
1149: }

1151: /*@
1152:   SNESResetFromOptions - Sets various `SNES` and `KSP` parameters from user options ONLY if the `SNESSetFromOptions()` was previously set from options

1154:   Collective

1156:   Input Parameter:
1157: . snes - the `SNES` context

1159:   Level: beginner

1161: .seealso: [](ch_snes), `SNES`, `SNESSetFromOptions()`, `SNESSetOptionsPrefix()`
1162: @*/
1163: PetscErrorCode SNESResetFromOptions(SNES snes)
1164: {
1165:   PetscFunctionBegin;
1166:   if (snes->setfromoptionscalled) PetscCall(SNESSetFromOptions(snes));
1167:   PetscFunctionReturn(PETSC_SUCCESS);
1168: }

1170: /*@C
1171:   SNESSetComputeApplicationContext - Sets an optional function to compute a user-defined context for
1172:   the nonlinear solvers.

1174:   Logically Collective; No Fortran Support

1176:   Input Parameters:
1177: + snes    - the `SNES` context
1178: . compute - function to compute the context
1179: - destroy - function to destroy the context

1181:   Level: intermediate

1183:   Note:
1184:   This routine is useful if you are performing grid sequencing or using `SNESFAS` and need the appropriate context generated for each level.

1186:   Use `SNESSetApplicationContext()` to see the context immediately

1188: .seealso: [](ch_snes), `SNESGetApplicationContext()`, `SNESSetApplicationContext()`
1189: @*/
1190: PetscErrorCode SNESSetComputeApplicationContext(SNES snes, PetscErrorCode (*compute)(SNES, void **), PetscErrorCode (*destroy)(void **))
1191: {
1192:   PetscFunctionBegin;
1194:   snes->ops->usercompute = compute;
1195:   snes->ops->userdestroy = destroy;
1196:   PetscFunctionReturn(PETSC_SUCCESS);
1197: }

1199: /*@
1200:   SNESSetApplicationContext - Sets the optional user-defined context for the nonlinear solvers.

1202:   Logically Collective

1204:   Input Parameters:
1205: + snes - the `SNES` context
1206: - usrP - optional user context

1208:   Level: intermediate

1210:   Notes:
1211:   Users can provide a context when constructing the `SNES` options and then access it inside their function, Jacobian, or other evaluation function
1212:   with `SNESGetApplicationContext()`

1214:   To provide a function that computes the context for you use `SNESSetComputeApplicationContext()`

1216:   Fortran Notes:
1217:   You must write a Fortran interface definition for this
1218:   function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

1220: .seealso: [](ch_snes), `SNES`, `SNESSetComputeApplicationContext()`, `SNESGetApplicationContext()`
1221: @*/
1222: PetscErrorCode SNESSetApplicationContext(SNES snes, void *usrP)
1223: {
1224:   KSP ksp;

1226:   PetscFunctionBegin;
1228:   PetscCall(SNESGetKSP(snes, &ksp));
1229:   PetscCall(KSPSetApplicationContext(ksp, usrP));
1230:   snes->user = usrP;
1231:   PetscFunctionReturn(PETSC_SUCCESS);
1232: }

1234: /*@
1235:   SNESGetApplicationContext - Gets the user-defined context for the
1236:   nonlinear solvers set with `SNESGetApplicationContext()` or with `SNESSetComputeApplicationContext()`

1238:   Not Collective

1240:   Input Parameter:
1241: . snes - `SNES` context

1243:   Output Parameter:
1244: . usrP - user context

1246:   Level: intermediate

1248:   Fortran Notes:
1249:   You must write a Fortran interface definition for this
1250:   function that tells Fortran the Fortran derived data type that you are passing in as the ctx argument.

1252: .seealso: [](ch_snes), `SNESSetApplicationContext()`
1253: @*/
1254: PetscErrorCode SNESGetApplicationContext(SNES snes, void *usrP)
1255: {
1256:   PetscFunctionBegin;
1258:   *(void **)usrP = snes->user;
1259:   PetscFunctionReturn(PETSC_SUCCESS);
1260: }

1262: /*@
1263:   SNESSetUseMatrixFree - indicates that `SNES` should use matrix-free finite difference matrix vector products to apply the Jacobian.

1265:   Logically Collective

1267:   Input Parameters:
1268: + snes        - `SNES` context
1269: . mf_operator - use matrix-free only for the Amat used by `SNESSetJacobian()`, this means the user provided Pmat will continue to be used
1270: - mf          - use matrix-free for both the Amat and Pmat used by `SNESSetJacobian()`, both the Amat and Pmat set in `SNESSetJacobian()` will be ignored. With
1271:    this option no matrix element based preconditioners can be used in the linear solve since the matrix won't be explicitly available

1273:   Options Database Keys:
1274: + -snes_mf_operator - use matrix-free only for the mat operator
1275: . -snes_mf          - use matrix-free for both the mat and pmat operator
1276: . -snes_fd_color    - compute the Jacobian via coloring and finite differences.
1277: - -snes_fd          - compute the Jacobian via finite differences (slow)

1279:   Level: intermediate

1281:   Note:
1282:   `SNES` supports three approaches for computing (approximate) Jacobians: user provided via `SNESSetJacobian()`, matrix-free, and computing explicitly with
1283:   finite differences and coloring using `MatFDColoring`. It is also possible to use automatic differentiation and the `MatFDColoring` object.

1285: .seealso: [](ch_snes), `SNES`, `SNESGetUseMatrixFree()`, `MatCreateSNESMF()`, `SNESComputeJacobianDefaultColor()`
1286: @*/
1287: PetscErrorCode SNESSetUseMatrixFree(SNES snes, PetscBool mf_operator, PetscBool mf)
1288: {
1289:   PetscFunctionBegin;
1293:   snes->mf          = mf_operator ? PETSC_TRUE : mf;
1294:   snes->mf_operator = mf_operator;
1295:   PetscFunctionReturn(PETSC_SUCCESS);
1296: }

1298: /*@
1299:   SNESGetUseMatrixFree - indicates if the `SNES` uses matrix-free finite difference matrix vector products to apply the Jacobian.

1301:   Not Collective, but the resulting flags will be the same on all MPI ranks

1303:   Input Parameter:
1304: . snes - `SNES` context

1306:   Output Parameters:
1307: + mf_operator - use matrix-free only for the Amat used by `SNESSetJacobian()`, this means the user provided Pmat will continue to be used
1308: - mf          - use matrix-free for both the Amat and Pmat used by `SNESSetJacobian()`, both the Amat and Pmat set in `SNESSetJacobian()` will be ignored

1310:   Level: intermediate

1312: .seealso: [](ch_snes), `SNES`, `SNESSetUseMatrixFree()`, `MatCreateSNESMF()`
1313: @*/
1314: PetscErrorCode SNESGetUseMatrixFree(SNES snes, PetscBool *mf_operator, PetscBool *mf)
1315: {
1316:   PetscFunctionBegin;
1318:   if (mf) *mf = snes->mf;
1319:   if (mf_operator) *mf_operator = snes->mf_operator;
1320:   PetscFunctionReturn(PETSC_SUCCESS);
1321: }

1323: /*@
1324:   SNESGetIterationNumber - Gets the number of nonlinear iterations completed
1325:   at this time.

1327:   Not Collective

1329:   Input Parameter:
1330: . snes - `SNES` context

1332:   Output Parameter:
1333: . iter - iteration number

1335:   Level: intermediate

1337:   Notes:
1338:   For example, during the computation of iteration 2 this would return 1.

1340:   This is useful for using lagged Jacobians (where one does not recompute the
1341:   Jacobian at each `SNES` iteration). For example, the code
1342: .vb
1343:       ierr = SNESGetIterationNumber(snes,&it);
1344:       if (!(it % 2)) {
1345:         [compute Jacobian here]
1346:       }
1347: .ve
1348:   can be used in your function that computes the Jacobian to cause the Jacobian to be
1349:   recomputed every second `SNES` iteration. See also `SNESSetLagJacobian()`

1351:   After the `SNES` solve is complete this will return the number of nonlinear iterations used.

1353: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetLagJacobian()`, `SNESGetLinearSolveIterations()`
1354: @*/
1355: PetscErrorCode SNESGetIterationNumber(SNES snes, PetscInt *iter)
1356: {
1357:   PetscFunctionBegin;
1359:   PetscAssertPointer(iter, 2);
1360:   *iter = snes->iter;
1361:   PetscFunctionReturn(PETSC_SUCCESS);
1362: }

1364: /*@
1365:   SNESSetIterationNumber - Sets the current iteration number.

1367:   Not Collective

1369:   Input Parameters:
1370: + snes - `SNES` context
1371: - iter - iteration number

1373:   Level: developer

1375: .seealso: [](ch_snes), `SNESGetLinearSolveIterations()`
1376: @*/
1377: PetscErrorCode SNESSetIterationNumber(SNES snes, PetscInt iter)
1378: {
1379:   PetscFunctionBegin;
1381:   PetscCall(PetscObjectSAWsTakeAccess((PetscObject)snes));
1382:   snes->iter = iter;
1383:   PetscCall(PetscObjectSAWsGrantAccess((PetscObject)snes));
1384:   PetscFunctionReturn(PETSC_SUCCESS);
1385: }

1387: /*@
1388:   SNESGetNonlinearStepFailures - Gets the number of unsuccessful steps
1389:   attempted by the nonlinear solver.

1391:   Not Collective

1393:   Input Parameter:
1394: . snes - `SNES` context

1396:   Output Parameter:
1397: . nfails - number of unsuccessful steps attempted

1399:   Level: intermediate

1401:   Note:
1402:   This counter is reset to zero for each successive call to `SNESSolve()`.

1404: .seealso: [](ch_snes), `SNES`, `SNESGetMaxLinearSolveFailures()`, `SNESGetLinearSolveIterations()`, `SNESSetMaxLinearSolveFailures()`, `SNESGetLinearSolveFailures()`,
1405:           `SNESSetMaxNonlinearStepFailures()`, `SNESGetMaxNonlinearStepFailures()`
1406: @*/
1407: PetscErrorCode SNESGetNonlinearStepFailures(SNES snes, PetscInt *nfails)
1408: {
1409:   PetscFunctionBegin;
1411:   PetscAssertPointer(nfails, 2);
1412:   *nfails = snes->numFailures;
1413:   PetscFunctionReturn(PETSC_SUCCESS);
1414: }

1416: /*@
1417:   SNESSetMaxNonlinearStepFailures - Sets the maximum number of unsuccessful steps
1418:   attempted by the nonlinear solver before it gives up and generates an error

1420:   Not Collective

1422:   Input Parameters:
1423: + snes     - `SNES` context
1424: - maxFails - maximum of unsuccessful steps

1426:   Level: intermediate

1428: .seealso: [](ch_snes), `SNESSetErrorIfNotConverged()`, `SNESGetMaxLinearSolveFailures()`, `SNESGetLinearSolveIterations()`, `SNESSetMaxLinearSolveFailures()`, `SNESGetLinearSolveFailures()`,
1429:           `SNESGetMaxNonlinearStepFailures()`, `SNESGetNonlinearStepFailures()`
1430: @*/
1431: PetscErrorCode SNESSetMaxNonlinearStepFailures(SNES snes, PetscInt maxFails)
1432: {
1433:   PetscFunctionBegin;
1435:   snes->maxFailures = maxFails;
1436:   PetscFunctionReturn(PETSC_SUCCESS);
1437: }

1439: /*@
1440:   SNESGetMaxNonlinearStepFailures - Gets the maximum number of unsuccessful steps
1441:   attempted by the nonlinear solver before it gives up and generates an error

1443:   Not Collective

1445:   Input Parameter:
1446: . snes - `SNES` context

1448:   Output Parameter:
1449: . maxFails - maximum of unsuccessful steps

1451:   Level: intermediate

1453: .seealso: [](ch_snes), `SNESSetErrorIfNotConverged()`, `SNESGetMaxLinearSolveFailures()`, `SNESGetLinearSolveIterations()`, `SNESSetMaxLinearSolveFailures()`, `SNESGetLinearSolveFailures()`,
1454:           `SNESSetMaxNonlinearStepFailures()`, `SNESGetNonlinearStepFailures()`
1455: @*/
1456: PetscErrorCode SNESGetMaxNonlinearStepFailures(SNES snes, PetscInt *maxFails)
1457: {
1458:   PetscFunctionBegin;
1460:   PetscAssertPointer(maxFails, 2);
1461:   *maxFails = snes->maxFailures;
1462:   PetscFunctionReturn(PETSC_SUCCESS);
1463: }

1465: /*@
1466:   SNESGetNumberFunctionEvals - Gets the number of user provided function evaluations
1467:   done by the `SNES` object

1469:   Not Collective

1471:   Input Parameter:
1472: . snes - `SNES` context

1474:   Output Parameter:
1475: . nfuncs - number of evaluations

1477:   Level: intermediate

1479:   Note:
1480:   Reset every time `SNESSolve()` is called unless `SNESSetCountersReset()` is used.

1482: .seealso: [](ch_snes), `SNES`, `SNESGetMaxLinearSolveFailures()`, `SNESGetLinearSolveIterations()`, `SNESSetMaxLinearSolveFailures()`, `SNESGetLinearSolveFailures()`, `SNESSetCountersReset()`
1483: @*/
1484: PetscErrorCode SNESGetNumberFunctionEvals(SNES snes, PetscInt *nfuncs)
1485: {
1486:   PetscFunctionBegin;
1488:   PetscAssertPointer(nfuncs, 2);
1489:   *nfuncs = snes->nfuncs;
1490:   PetscFunctionReturn(PETSC_SUCCESS);
1491: }

1493: /*@
1494:   SNESGetLinearSolveFailures - Gets the number of failed (non-converged)
1495:   linear solvers.

1497:   Not Collective

1499:   Input Parameter:
1500: . snes - `SNES` context

1502:   Output Parameter:
1503: . nfails - number of failed solves

1505:   Options Database Key:
1506: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated

1508:   Level: intermediate

1510:   Note:
1511:   This counter is reset to zero for each successive call to `SNESSolve()`.

1513: .seealso: [](ch_snes), `SNESGetMaxLinearSolveFailures()`, `SNESGetLinearSolveIterations()`, `SNESSetMaxLinearSolveFailures()`
1514: @*/
1515: PetscErrorCode SNESGetLinearSolveFailures(SNES snes, PetscInt *nfails)
1516: {
1517:   PetscFunctionBegin;
1519:   PetscAssertPointer(nfails, 2);
1520:   *nfails = snes->numLinearSolveFailures;
1521:   PetscFunctionReturn(PETSC_SUCCESS);
1522: }

1524: /*@
1525:   SNESSetMaxLinearSolveFailures - the number of failed linear solve attempts
1526:   allowed before `SNES` returns with a diverged reason of `SNES_DIVERGED_LINEAR_SOLVE`

1528:   Logically Collective

1530:   Input Parameters:
1531: + snes     - `SNES` context
1532: - maxFails - maximum allowed linear solve failures

1534:   Options Database Key:
1535: . -snes_max_linear_solve_fail <num> - The number of failures before the solve is terminated

1537:   Level: intermediate

1539:   Note:
1540:   By default this is 0; that is `SNES` returns on the first failed linear solve

1542: .seealso: [](ch_snes), `SNESSetErrorIfNotConverged()`, `SNESGetLinearSolveFailures()`, `SNESGetMaxLinearSolveFailures()`, `SNESGetLinearSolveIterations()`
1543: @*/
1544: PetscErrorCode SNESSetMaxLinearSolveFailures(SNES snes, PetscInt maxFails)
1545: {
1546:   PetscFunctionBegin;
1549:   snes->maxLinearSolveFailures = maxFails;
1550:   PetscFunctionReturn(PETSC_SUCCESS);
1551: }

1553: /*@
1554:   SNESGetMaxLinearSolveFailures - gets the maximum number of linear solve failures that
1555:   are allowed before `SNES` returns as unsuccessful

1557:   Not Collective

1559:   Input Parameter:
1560: . snes - `SNES` context

1562:   Output Parameter:
1563: . maxFails - maximum of unsuccessful solves allowed

1565:   Level: intermediate

1567:   Note:
1568:   By default this is 1; that is `SNES` returns on the first failed linear solve

1570: .seealso: [](ch_snes), `SNESSetErrorIfNotConverged()`, `SNESGetLinearSolveFailures()`, `SNESGetLinearSolveIterations()`, `SNESSetMaxLinearSolveFailures()`,
1571: @*/
1572: PetscErrorCode SNESGetMaxLinearSolveFailures(SNES snes, PetscInt *maxFails)
1573: {
1574:   PetscFunctionBegin;
1576:   PetscAssertPointer(maxFails, 2);
1577:   *maxFails = snes->maxLinearSolveFailures;
1578:   PetscFunctionReturn(PETSC_SUCCESS);
1579: }

1581: /*@
1582:   SNESGetLinearSolveIterations - Gets the total number of linear iterations
1583:   used by the nonlinear solver.

1585:   Not Collective

1587:   Input Parameter:
1588: . snes - `SNES` context

1590:   Output Parameter:
1591: . lits - number of linear iterations

1593:   Level: intermediate

1595:   Notes:
1596:   This counter is reset to zero for each successive call to `SNESSolve()` unless `SNESSetCountersReset()` is used.

1598:   If the linear solver fails inside the `SNESSolve()` the iterations for that call to the linear solver are not included. If you wish to count them
1599:   then call `KSPGetIterationNumber()` after the failed solve.

1601: .seealso: [](ch_snes), `SNES`, `SNESGetIterationNumber()`, `SNESGetLinearSolveFailures()`, `SNESGetMaxLinearSolveFailures()`, `SNESSetCountersReset()`
1602: @*/
1603: PetscErrorCode SNESGetLinearSolveIterations(SNES snes, PetscInt *lits)
1604: {
1605:   PetscFunctionBegin;
1607:   PetscAssertPointer(lits, 2);
1608:   *lits = snes->linear_its;
1609:   PetscFunctionReturn(PETSC_SUCCESS);
1610: }

1612: /*@
1613:   SNESSetCountersReset - Sets whether or not the counters for linear iterations and function evaluations
1614:   are reset every time `SNESSolve()` is called.

1616:   Logically Collective

1618:   Input Parameters:
1619: + snes  - `SNES` context
1620: - reset - whether to reset the counters or not, defaults to `PETSC_TRUE`

1622:   Level: developer

1624: .seealso: [](ch_snes), `SNESGetNumberFunctionEvals()`, `SNESGetLinearSolveIterations()`, `SNESGetNPC()`
1625: @*/
1626: PetscErrorCode SNESSetCountersReset(SNES snes, PetscBool reset)
1627: {
1628:   PetscFunctionBegin;
1631:   snes->counters_reset = reset;
1632:   PetscFunctionReturn(PETSC_SUCCESS);
1633: }

1635: /*@
1636:   SNESSetKSP - Sets a `KSP` context for the `SNES` object to use

1638:   Not Collective, but the `SNES` and `KSP` objects must live on the same MPI_Comm

1640:   Input Parameters:
1641: + snes - the `SNES` context
1642: - ksp  - the `KSP` context

1644:   Level: developer

1646:   Notes:
1647:   The `SNES` object already has its `KSP` object, you can obtain with `SNESGetKSP()`
1648:   so this routine is rarely needed.

1650:   The `KSP` object that is already in the `SNES` object has its reference count
1651:   decreased by one.

1653: .seealso: [](ch_snes), `SNES`, `KSP`, `KSPGetPC()`, `SNESCreate()`, `KSPCreate()`
1654: @*/
1655: PetscErrorCode SNESSetKSP(SNES snes, KSP ksp)
1656: {
1657:   PetscFunctionBegin;
1660:   PetscCheckSameComm(snes, 1, ksp, 2);
1661:   PetscCall(PetscObjectReference((PetscObject)ksp));
1662:   if (snes->ksp) PetscCall(PetscObjectDereference((PetscObject)snes->ksp));
1663:   snes->ksp = ksp;
1664:   PetscFunctionReturn(PETSC_SUCCESS);
1665: }

1667: /*@
1668:   SNESCreate - Creates a nonlinear solver context used to manage a set of nonlinear solves

1670:   Collective

1672:   Input Parameter:
1673: . comm - MPI communicator

1675:   Output Parameter:
1676: . outsnes - the new `SNES` context

1678:   Options Database Keys:
1679: + -snes_mf          - Activates default matrix-free Jacobian-vector products, and no preconditioning matrix
1680: . -snes_mf_operator - Activates default matrix-free Jacobian-vector products, and a user-provided preconditioning matrix
1681:                as set by `SNESSetJacobian()`
1682: . -snes_fd_coloring - uses a relative fast computation of the Jacobian using finite differences and a graph coloring
1683: - -snes_fd          - Uses (slow!) finite differences to compute Jacobian

1685:   Level: beginner

1687:   Developer Notes:
1688:   `SNES` always creates a `KSP` object even though many `SNES` methods do not use it. This is
1689:   unfortunate and should be fixed at some point. The flag snes->usesksp indicates if the
1690:   particular method does use `KSP` and regulates if the information about the `KSP` is printed
1691:   in `SNESView()`.

1693:   `TSSetFromOptions()` does call `SNESSetFromOptions()` which can lead to users being confused
1694:   by help messages about meaningless `SNES` options.

1696:   `SNES` always creates the snes->kspconvctx even though it is used by only one type. This should be fixed.

1698: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESDestroy()`, `SNESSetLagPreconditioner()`, `SNESSetLagJacobian()`
1699: @*/
1700: PetscErrorCode SNESCreate(MPI_Comm comm, SNES *outsnes)
1701: {
1702:   SNES       snes;
1703:   SNESKSPEW *kctx;

1705:   PetscFunctionBegin;
1706:   PetscAssertPointer(outsnes, 2);
1707:   *outsnes = NULL;
1708:   PetscCall(SNESInitializePackage());

1710:   PetscCall(PetscHeaderCreate(snes, SNES_CLASSID, "SNES", "Nonlinear solver", "SNES", comm, SNESDestroy, SNESView));

1712:   snes->ops->converged       = SNESConvergedDefault;
1713:   snes->usesksp              = PETSC_TRUE;
1714:   snes->tolerancesset        = PETSC_FALSE;
1715:   snes->max_its              = 50;
1716:   snes->max_funcs            = 10000;
1717:   snes->norm                 = 0.0;
1718:   snes->xnorm                = 0.0;
1719:   snes->ynorm                = 0.0;
1720:   snes->normschedule         = SNES_NORM_ALWAYS;
1721:   snes->functype             = SNES_FUNCTION_DEFAULT;
1722:   snes->rtol                 = PetscDefined(USE_REAL_SINGLE) ? 1.e-5 : 1.e-8;
1723:   snes->ttol                 = 0.0;
1724:   snes->abstol               = PetscDefined(USE_REAL_SINGLE) ? 1.e-25 : 1.e-50;
1725:   snes->stol                 = PetscDefined(USE_REAL_SINGLE) ? 1.e-5 : 1.e-8;
1726:   snes->deltatol             = PetscDefined(USE_REAL_SINGLE) ? 1.e-6 : 1.e-12;
1727:   snes->divtol               = 1.e4;
1728:   snes->rnorm0               = 0;
1729:   snes->nfuncs               = 0;
1730:   snes->numFailures          = 0;
1731:   snes->maxFailures          = 1;
1732:   snes->linear_its           = 0;
1733:   snes->lagjacobian          = 1;
1734:   snes->jac_iter             = 0;
1735:   snes->lagjac_persist       = PETSC_FALSE;
1736:   snes->lagpreconditioner    = 1;
1737:   snes->pre_iter             = 0;
1738:   snes->lagpre_persist       = PETSC_FALSE;
1739:   snes->numbermonitors       = 0;
1740:   snes->numberreasonviews    = 0;
1741:   snes->data                 = NULL;
1742:   snes->setupcalled          = PETSC_FALSE;
1743:   snes->ksp_ewconv           = PETSC_FALSE;
1744:   snes->nwork                = 0;
1745:   snes->work                 = NULL;
1746:   snes->nvwork               = 0;
1747:   snes->vwork                = NULL;
1748:   snes->conv_hist_len        = 0;
1749:   snes->conv_hist_max        = 0;
1750:   snes->conv_hist            = NULL;
1751:   snes->conv_hist_its        = NULL;
1752:   snes->conv_hist_reset      = PETSC_TRUE;
1753:   snes->counters_reset       = PETSC_TRUE;
1754:   snes->vec_func_init_set    = PETSC_FALSE;
1755:   snes->reason               = SNES_CONVERGED_ITERATING;
1756:   snes->npcside              = PC_RIGHT;
1757:   snes->setfromoptionscalled = 0;

1759:   snes->mf          = PETSC_FALSE;
1760:   snes->mf_operator = PETSC_FALSE;
1761:   snes->mf_version  = 1;

1763:   snes->numLinearSolveFailures = 0;
1764:   snes->maxLinearSolveFailures = 1;

1766:   snes->vizerotolerance     = 1.e-8;
1767:   snes->checkjacdomainerror = PetscDefined(USE_DEBUG) ? PETSC_TRUE : PETSC_FALSE;

1769:   /* Set this to true if the implementation of SNESSolve_XXX does compute the residual at the final solution. */
1770:   snes->alwayscomputesfinalresidual = PETSC_FALSE;

1772:   /* Create context to compute Eisenstat-Walker relative tolerance for KSP */
1773:   PetscCall(PetscNew(&kctx));

1775:   snes->kspconvctx  = (void *)kctx;
1776:   kctx->version     = 2;
1777:   kctx->rtol_0      = 0.3; /* Eisenstat and Walker suggest rtol_0=.5, but
1778:                              this was too large for some test cases */
1779:   kctx->rtol_last   = 0.0;
1780:   kctx->rtol_max    = 0.9;
1781:   kctx->gamma       = 1.0;
1782:   kctx->alpha       = 0.5 * (1.0 + PetscSqrtReal(5.0));
1783:   kctx->alpha2      = kctx->alpha;
1784:   kctx->threshold   = 0.1;
1785:   kctx->lresid_last = 0.0;
1786:   kctx->norm_last   = 0.0;

1788:   kctx->rk_last     = 0.0;
1789:   kctx->rk_last_2   = 0.0;
1790:   kctx->rtol_last_2 = 0.0;
1791:   kctx->v4_p1       = 0.1;
1792:   kctx->v4_p2       = 0.4;
1793:   kctx->v4_p3       = 0.7;
1794:   kctx->v4_m1       = 0.8;
1795:   kctx->v4_m2       = 0.5;
1796:   kctx->v4_m3       = 0.1;
1797:   kctx->v4_m4       = 0.5;

1799:   *outsnes = snes;
1800:   PetscFunctionReturn(PETSC_SUCCESS);
1801: }

1803: /*MC
1804:     SNESFunction - Functional form used to convey the nonlinear function to `SNES` in `SNESSetFunction()`

1806:      Synopsis:
1807:      #include "petscsnes.h"
1808:      PetscErrorCode SNESFunction(SNES snes,Vec x,Vec f,void *ctx);

1810:      Collective

1812:      Input Parameters:
1813: +     snes - the `SNES` context
1814: .     x    - state at which to evaluate residual
1815: -     ctx     - optional user-defined function context, passed in with `SNESSetFunction()`

1817:      Output Parameter:
1818: .     f  - vector to put residual (function value)

1820:    Level: intermediate

1822: .seealso: [](ch_snes), `SNESSetFunction()`, `SNESGetFunction()`
1823: M*/

1825: /*@C
1826:   SNESSetFunction - Sets the function evaluation routine and function
1827:   vector for use by the `SNES` routines in solving systems of nonlinear
1828:   equations.

1830:   Logically Collective

1832:   Input Parameters:
1833: + snes - the `SNES` context
1834: . r    - vector to store function values, may be `NULL`
1835: . f    - function evaluation routine;  for calling sequence see `SNESFunction`
1836: - ctx  - [optional] user-defined context for private data for the
1837:          function evaluation routine (may be `NULL`)

1839:   Level: beginner

1841: .seealso: [](ch_snes), `SNES`, `SNESGetFunction()`, `SNESComputeFunction()`, `SNESSetJacobian()`, `SNESSetPicard()`, `SNESFunction`
1842: @*/
1843: PetscErrorCode SNESSetFunction(SNES snes, Vec r, PetscErrorCode (*f)(SNES, Vec, Vec, void *), void *ctx)
1844: {
1845:   DM dm;

1847:   PetscFunctionBegin;
1849:   if (r) {
1851:     PetscCheckSameComm(snes, 1, r, 2);
1852:     PetscCall(PetscObjectReference((PetscObject)r));
1853:     PetscCall(VecDestroy(&snes->vec_func));
1854:     snes->vec_func = r;
1855:   }
1856:   PetscCall(SNESGetDM(snes, &dm));
1857:   PetscCall(DMSNESSetFunction(dm, f, ctx));
1858:   if (f == SNESPicardComputeFunction) PetscCall(DMSNESSetMFFunction(dm, SNESPicardComputeMFFunction, ctx));
1859:   PetscFunctionReturn(PETSC_SUCCESS);
1860: }

1862: /*@C
1863:   SNESSetInitialFunction - Set an already computed function evaluation at the initial guess to be reused by `SNESSolve()`.

1865:   Logically Collective

1867:   Input Parameters:
1868: + snes - the `SNES` context
1869: - f    - vector to store function value

1871:   Level: developer

1873:   Notes:
1874:   This should not be modified during the solution procedure.

1876:   This is used extensively in the `SNESFAS` hierarchy and in nonlinear preconditioning.

1878: .seealso: [](ch_snes), `SNES`, `SNESFAS`, `SNESSetFunction()`, `SNESComputeFunction()`, `SNESSetInitialFunctionNorm()`
1879: @*/
1880: PetscErrorCode SNESSetInitialFunction(SNES snes, Vec f)
1881: {
1882:   Vec vec_func;

1884:   PetscFunctionBegin;
1887:   PetscCheckSameComm(snes, 1, f, 2);
1888:   if (snes->npcside == PC_LEFT && snes->functype == SNES_FUNCTION_PRECONDITIONED) {
1889:     snes->vec_func_init_set = PETSC_FALSE;
1890:     PetscFunctionReturn(PETSC_SUCCESS);
1891:   }
1892:   PetscCall(SNESGetFunction(snes, &vec_func, NULL, NULL));
1893:   PetscCall(VecCopy(f, vec_func));

1895:   snes->vec_func_init_set = PETSC_TRUE;
1896:   PetscFunctionReturn(PETSC_SUCCESS);
1897: }

1899: /*@
1900:   SNESSetNormSchedule - Sets the `SNESNormSchedule` used in convergence and monitoring
1901:   of the `SNES` method, when norms are computed in the solving process

1903:   Logically Collective

1905:   Input Parameters:
1906: + snes         - the `SNES` context
1907: - normschedule - the frequency of norm computation

1909:   Options Database Key:
1910: . -snes_norm_schedule <none, always, initialonly, finalonly, initialfinalonly> - set the schedule

1912:   Level: advanced

1914:   Notes:
1915:   Only certain `SNES` methods support certain `SNESNormSchedules`.  Most require evaluation
1916:   of the nonlinear function and the taking of its norm at every iteration to
1917:   even ensure convergence at all.  However, methods such as custom Gauss-Seidel methods
1918:   `SNESNGS` and the like do not require the norm of the function to be computed, and therefore
1919:   may either be monitored for convergence or not.  As these are often used as nonlinear
1920:   preconditioners, monitoring the norm of their error is not a useful enterprise within
1921:   their solution.

1923: .seealso: [](ch_snes), `SNESNormSchedule`, `SNESGetNormSchedule()`, `SNESComputeFunction()`, `VecNorm()`, `SNESSetFunction()`, `SNESSetInitialFunction()`
1924: @*/
1925: PetscErrorCode SNESSetNormSchedule(SNES snes, SNESNormSchedule normschedule)
1926: {
1927:   PetscFunctionBegin;
1929:   snes->normschedule = normschedule;
1930:   PetscFunctionReturn(PETSC_SUCCESS);
1931: }

1933: /*@
1934:   SNESGetNormSchedule - Gets the `SNESNormSchedule` used in convergence and monitoring
1935:   of the `SNES` method.

1937:   Logically Collective

1939:   Input Parameters:
1940: + snes         - the `SNES` context
1941: - normschedule - the type of the norm used

1943:   Level: advanced

1945: .seealso: [](ch_snes), `SNES`, `SNESSetNormSchedule()`, `SNESComputeFunction()`, `VecNorm()`, `SNESSetFunction()`, `SNESSetInitialFunction()`, `SNESNormSchedule`
1946: @*/
1947: PetscErrorCode SNESGetNormSchedule(SNES snes, SNESNormSchedule *normschedule)
1948: {
1949:   PetscFunctionBegin;
1951:   *normschedule = snes->normschedule;
1952:   PetscFunctionReturn(PETSC_SUCCESS);
1953: }

1955: /*@
1956:   SNESSetFunctionNorm - Sets the last computed residual norm.

1958:   Logically Collective

1960:   Input Parameters:
1961: + snes - the `SNES` context
1962: - norm - the value of the norm

1964:   Level: developer

1966: .seealso: [](ch_snes), `SNES`, `SNESGetNormSchedule()`, `SNESComputeFunction()`, `VecNorm()`, `SNESSetFunction()`, `SNESSetInitialFunction()`, `SNESNormSchedule`
1967: @*/
1968: PetscErrorCode SNESSetFunctionNorm(SNES snes, PetscReal norm)
1969: {
1970:   PetscFunctionBegin;
1972:   snes->norm = norm;
1973:   PetscFunctionReturn(PETSC_SUCCESS);
1974: }

1976: /*@
1977:   SNESGetFunctionNorm - Gets the last computed norm of the residual

1979:   Not Collective

1981:   Input Parameter:
1982: . snes - the `SNES` context

1984:   Output Parameter:
1985: . norm - the last computed residual norm

1987:   Level: developer

1989: .seealso: [](ch_snes), `SNES`, `SNESSetNormSchedule()`, `SNESComputeFunction()`, `VecNorm()`, `SNESSetFunction()`, `SNESSetInitialFunction()`, `SNESNormSchedule`
1990: @*/
1991: PetscErrorCode SNESGetFunctionNorm(SNES snes, PetscReal *norm)
1992: {
1993:   PetscFunctionBegin;
1995:   PetscAssertPointer(norm, 2);
1996:   *norm = snes->norm;
1997:   PetscFunctionReturn(PETSC_SUCCESS);
1998: }

2000: /*@
2001:   SNESGetUpdateNorm - Gets the last computed norm of the solution update

2003:   Not Collective

2005:   Input Parameter:
2006: . snes - the `SNES` context

2008:   Output Parameter:
2009: . ynorm - the last computed update norm

2011:   Level: developer

2013:   Note:
2014:   The new solution is the current solution plus the update, so this norm is an indication of the size of the update

2016: .seealso: [](ch_snes), `SNES`, `SNESSetNormSchedule()`, `SNESComputeFunction()`, `SNESGetFunctionNorm()`
2017: @*/
2018: PetscErrorCode SNESGetUpdateNorm(SNES snes, PetscReal *ynorm)
2019: {
2020:   PetscFunctionBegin;
2022:   PetscAssertPointer(ynorm, 2);
2023:   *ynorm = snes->ynorm;
2024:   PetscFunctionReturn(PETSC_SUCCESS);
2025: }

2027: /*@
2028:   SNESGetSolutionNorm - Gets the last computed norm of the solution

2030:   Not Collective

2032:   Input Parameter:
2033: . snes - the `SNES` context

2035:   Output Parameter:
2036: . xnorm - the last computed solution norm

2038:   Level: developer

2040: .seealso: [](ch_snes), `SNES`, `SNESSetNormSchedule()`, `SNESComputeFunction()`, `SNESGetFunctionNorm()`, `SNESGetUpdateNorm()`
2041: @*/
2042: PetscErrorCode SNESGetSolutionNorm(SNES snes, PetscReal *xnorm)
2043: {
2044:   PetscFunctionBegin;
2046:   PetscAssertPointer(xnorm, 2);
2047:   *xnorm = snes->xnorm;
2048:   PetscFunctionReturn(PETSC_SUCCESS);
2049: }

2051: /*@C
2052:   SNESSetFunctionType - Sets the `SNESFunctionType`
2053:   of the `SNES` method.

2055:   Logically Collective

2057:   Input Parameters:
2058: + snes - the `SNES` context
2059: - type - the function type

2061:   Level: developer

2063:   Notes:
2064:   Possible values of the function type
2065: +  `SNES_FUNCTION_DEFAULT` - the default for the given `SNESType`
2066: .  `SNES_FUNCTION_UNPRECONDITIONED` - an unpreconditioned function evaluation (this is the function provided with `SNESSetFunction()`
2067: -  `SNES_FUNCTION_PRECONDITIONED` - a transformation of the function provided with `SNESSetFunction()`

2069:   Different `SNESType`s use this value in different ways

2071: .seealso: [](ch_snes), `SNES`, `SNESFunctionType`, `SNESGetNormSchedule()`, `SNESComputeFunction()`, `VecNorm()`, `SNESSetFunction()`, `SNESSetInitialFunction()`, `SNESNormSchedule`
2072: @*/
2073: PetscErrorCode SNESSetFunctionType(SNES snes, SNESFunctionType type)
2074: {
2075:   PetscFunctionBegin;
2077:   snes->functype = type;
2078:   PetscFunctionReturn(PETSC_SUCCESS);
2079: }

2081: /*@C
2082:   SNESGetFunctionType - Gets the `SNESFunctionType` used in convergence and monitoring set with `SNESSetFunctionType()`
2083:   of the SNES method.

2085:   Logically Collective

2087:   Input Parameters:
2088: + snes - the `SNES` context
2089: - type - the type of the function evaluation, see `SNESSetFunctionType()`

2091:   Level: advanced

2093: .seealso: [](ch_snes), `SNESSetFunctionType()`, `SNESFunctionType`, `SNESSetNormSchedule()`, `SNESComputeFunction()`, `VecNorm()`, `SNESSetFunction()`, `SNESSetInitialFunction()`, `SNESNormSchedule`
2094: @*/
2095: PetscErrorCode SNESGetFunctionType(SNES snes, SNESFunctionType *type)
2096: {
2097:   PetscFunctionBegin;
2099:   *type = snes->functype;
2100:   PetscFunctionReturn(PETSC_SUCCESS);
2101: }

2103: /*@C
2104:   SNESSetNGS - Sets the user nonlinear Gauss-Seidel routine for
2105:   use with composed nonlinear solvers.

2107:   Input Parameters:
2108: + snes - the `SNES` context
2109: . f    - function evaluation routine to apply Gauss-Seidel
2110: - ctx  - [optional] user-defined context for private data for the
2111:             smoother evaluation routine (may be `NULL`)

2113:   Calling sequence of `f`:
2114: $ PetscErrorCode f(SNES snes, Vec X, Vec B, void *ctx);
2115: + snes - the `SNES` context
2116: . X    - the current solution
2117: . B    - the right hand side vector (which may be `NULL`)
2118: - ctx  - a user provided context

2120:   Level: intermediate

2122:   Note:
2123:   The `SNESNGS` routines are used by the composed nonlinear solver to generate
2124:   a problem appropriate update to the solution, particularly `SNESFAS`.

2126: .seealso: [](ch_snes), `SNESGetNGS()`, `SNESNCG`, `SNESGetFunction()`, `SNESComputeNGS()`
2127: @*/
2128: PetscErrorCode SNESSetNGS(SNES snes, PetscErrorCode (*f)(SNES snes, Vec X, Vec B, void *ctx), void *ctx)
2129: {
2130:   DM dm;

2132:   PetscFunctionBegin;
2134:   PetscCall(SNESGetDM(snes, &dm));
2135:   PetscCall(DMSNESSetNGS(dm, f, ctx));
2136:   PetscFunctionReturn(PETSC_SUCCESS);
2137: }

2139: /*
2140:      This is used for -snes_mf_operator; it uses a duplicate of snes->jacobian_pre because snes->jacobian_pre cannot be
2141:    changed during the KSPSolve()
2142: */
2143: PetscErrorCode SNESPicardComputeMFFunction(SNES snes, Vec x, Vec f, void *ctx)
2144: {
2145:   DM     dm;
2146:   DMSNES sdm;

2148:   PetscFunctionBegin;
2149:   PetscCall(SNESGetDM(snes, &dm));
2150:   PetscCall(DMGetDMSNES(dm, &sdm));
2151:   /*  A(x)*x - b(x) */
2152:   if (sdm->ops->computepfunction) {
2153:     PetscCallBack("SNES Picard callback function", (*sdm->ops->computepfunction)(snes, x, f, sdm->pctx));
2154:     PetscCall(VecScale(f, -1.0));
2155:     /* Cannot share nonzero pattern because of the possible use of SNESComputeJacobianDefault() */
2156:     if (!snes->picard) PetscCall(MatDuplicate(snes->jacobian_pre, MAT_DO_NOT_COPY_VALUES, &snes->picard));
2157:     PetscCallBack("SNES Picard callback Jacobian", (*sdm->ops->computepjacobian)(snes, x, snes->picard, snes->picard, sdm->pctx));
2158:     PetscCall(MatMultAdd(snes->picard, x, f, f));
2159:   } else {
2160:     PetscCallBack("SNES Picard callback Jacobian", (*sdm->ops->computepjacobian)(snes, x, snes->picard, snes->picard, sdm->pctx));
2161:     PetscCall(MatMult(snes->picard, x, f));
2162:   }
2163:   PetscFunctionReturn(PETSC_SUCCESS);
2164: }

2166: PetscErrorCode SNESPicardComputeFunction(SNES snes, Vec x, Vec f, void *ctx)
2167: {
2168:   DM     dm;
2169:   DMSNES sdm;

2171:   PetscFunctionBegin;
2172:   PetscCall(SNESGetDM(snes, &dm));
2173:   PetscCall(DMGetDMSNES(dm, &sdm));
2174:   /*  A(x)*x - b(x) */
2175:   if (sdm->ops->computepfunction) {
2176:     PetscCallBack("SNES Picard callback function", (*sdm->ops->computepfunction)(snes, x, f, sdm->pctx));
2177:     PetscCall(VecScale(f, -1.0));
2178:     PetscCallBack("SNES Picard callback Jacobian", (*sdm->ops->computepjacobian)(snes, x, snes->jacobian, snes->jacobian_pre, sdm->pctx));
2179:     PetscCall(MatMultAdd(snes->jacobian_pre, x, f, f));
2180:   } else {
2181:     PetscCallBack("SNES Picard callback Jacobian", (*sdm->ops->computepjacobian)(snes, x, snes->jacobian, snes->jacobian_pre, sdm->pctx));
2182:     PetscCall(MatMult(snes->jacobian_pre, x, f));
2183:   }
2184:   PetscFunctionReturn(PETSC_SUCCESS);
2185: }

2187: PetscErrorCode SNESPicardComputeJacobian(SNES snes, Vec x1, Mat J, Mat B, void *ctx)
2188: {
2189:   PetscFunctionBegin;
2190:   /* the jacobian matrix should be pre-filled in SNESPicardComputeFunction */
2191:   /* must assembly if matrix-free to get the last SNES solution */
2192:   PetscCall(MatAssemblyBegin(J, MAT_FINAL_ASSEMBLY));
2193:   PetscCall(MatAssemblyEnd(J, MAT_FINAL_ASSEMBLY));
2194:   PetscFunctionReturn(PETSC_SUCCESS);
2195: }

2197: /*@C
2198:   SNESSetPicard - Use `SNES` to solve the system A(x) x = bp(x) + b via a Picard type iteration (Picard linearization)

2200:   Logically Collective

2202:   Input Parameters:
2203: + snes - the `SNES` context
2204: . r    - vector to store function values, may be `NULL`
2205: . bp   - function evaluation routine, may be `NULL`
2206: . Amat - matrix with which A(x) x - bp(x) - b is to be computed
2207: . Pmat - matrix from which preconditioner is computed (usually the same as `Amat`)
2208: . J    - function to compute matrix values, for the calling sequence see `SNESJacobianFunction()`
2209: - ctx  - [optional] user-defined context for private data for the function evaluation routine (may be `NULL`)

2211:   Level: intermediate

2213:   Notes:
2214:   It is often better to provide the nonlinear function F() and some approximation to its Jacobian directly and use
2215:   an approximate Newton solver. This interface is provided to allow porting/testing a previous Picard based code in PETSc before converting it to approximate Newton.

2217:   One can call `SNESSetPicard()` or `SNESSetFunction()` (and possibly `SNESSetJacobian()`) but cannot call both

2219:   Solves the equation A(x) x = bp(x) - b via the defect correction algorithm A(x^{n}) (x^{n+1} - x^{n}) = bp(x^{n}) + b - A(x^{n})x^{n}.
2220:   When an exact solver is used this corresponds to the "classic" Picard A(x^{n}) x^{n+1} = bp(x^{n}) + b iteration.

2222:   Run with `-snes_mf_operator` to solve the system with Newton's method using A(x^{n}) to construct the preconditioner.

2224:   We implement the defect correction form of the Picard iteration because it converges much more generally when inexact linear solvers are used then
2225:   the direct Picard iteration A(x^n) x^{n+1} = bp(x^n) + b

2227:   There is some controversity over the definition of a Picard iteration for nonlinear systems but almost everyone agrees that it involves a linear solve and some
2228:   believe it is the iteration  A(x^{n}) x^{n+1} = b(x^{n}) hence we use the name Picard. If anyone has an authoritative  reference that defines the Picard iteration
2229:   different please contact us at petsc-dev@mcs.anl.gov and we'll have an entirely new argument :-).

2231:   When used with `-snes_mf_operator` this will run matrix-free Newton's method where the matrix-vector product is of the true Jacobian of A(x)x - bp(x) -b and
2232:   A(x^{n}) is used to build the preconditioner

2234:   When used with `-snes_fd` this will compute the true Jacobian (very slowly one column at at time) and thus represent Newton's method.

2236:   When used with `-snes_fd_coloring` this will compute the Jacobian via coloring and thus represent a faster implementation of Newton's method. But the
2237:   the nonzero structure of the Jacobian is, in general larger than that of the Picard matrix A so you must provide in A the needed nonzero structure for the correct
2238:   coloring. When using `DMDA` this may mean creating the matrix A with `DMCreateMatrix()` using a wider stencil than strictly needed for A or with a `DMDA_STENCIL_BOX`.
2239:   See the comment in src/snes/tutorials/ex15.c.

2241: .seealso: [](ch_snes), `SNES`, `SNESGetFunction()`, `SNESSetFunction()`, `SNESComputeFunction()`, `SNESSetJacobian()`, `SNESGetPicard()`, `SNESLineSearchPreCheckPicard()`, `SNESJacobianFunction`
2242: @*/
2243: PetscErrorCode SNESSetPicard(SNES snes, Vec r, PetscErrorCode (*bp)(SNES, Vec, Vec, void *), Mat Amat, Mat Pmat, PetscErrorCode (*J)(SNES, Vec, Mat, Mat, void *), void *ctx)
2244: {
2245:   DM dm;

2247:   PetscFunctionBegin;
2249:   PetscCall(SNESGetDM(snes, &dm));
2250:   PetscCall(DMSNESSetPicard(dm, bp, J, ctx));
2251:   PetscCall(DMSNESSetMFFunction(dm, SNESPicardComputeMFFunction, ctx));
2252:   PetscCall(SNESSetFunction(snes, r, SNESPicardComputeFunction, ctx));
2253:   PetscCall(SNESSetJacobian(snes, Amat, Pmat, SNESPicardComputeJacobian, ctx));
2254:   PetscFunctionReturn(PETSC_SUCCESS);
2255: }

2257: /*@C
2258:   SNESGetPicard - Returns the context for the Picard iteration

2260:   Not Collective, but `Vec` is parallel if `SNES` is parallel. Collective if `Vec` is requested, but has not been created yet.

2262:   Input Parameter:
2263: . snes - the `SNES` context

2265:   Output Parameters:
2266: + r    - the function (or `NULL`)
2267: . f    - the function (or `NULL`);  for calling sequence see `SNESFunction`
2268: . Amat - the matrix used to defined the operation A(x) x - b(x) (or `NULL`)
2269: . Pmat - the matrix from which the preconditioner will be constructed (or `NULL`)
2270: . J    - the function for matrix evaluation (or `NULL`);  for calling sequence see `SNESJacobianFunction`
2271: - ctx  - the function context (or `NULL`)

2273:   Level: advanced

2275: .seealso: [](ch_snes), `SNESSetFunction()`, `SNESSetPicard()`, `SNESGetFunction()`, `SNESGetJacobian()`, `SNESGetDM()`, `SNESFunction`, `SNESJacobianFunction`
2276: @*/
2277: PetscErrorCode SNESGetPicard(SNES snes, Vec *r, PetscErrorCode (**f)(SNES, Vec, Vec, void *), Mat *Amat, Mat *Pmat, PetscErrorCode (**J)(SNES, Vec, Mat, Mat, void *), void **ctx)
2278: {
2279:   DM dm;

2281:   PetscFunctionBegin;
2283:   PetscCall(SNESGetFunction(snes, r, NULL, NULL));
2284:   PetscCall(SNESGetJacobian(snes, Amat, Pmat, NULL, NULL));
2285:   PetscCall(SNESGetDM(snes, &dm));
2286:   PetscCall(DMSNESGetPicard(dm, f, J, ctx));
2287:   PetscFunctionReturn(PETSC_SUCCESS);
2288: }

2290: /*@C
2291:   SNESSetComputeInitialGuess - Sets a routine used to compute an initial guess for the nonlinear problem

2293:   Logically Collective

2295:   Input Parameters:
2296: + snes - the `SNES` context
2297: . func - function evaluation routine
2298: - ctx  - [optional] user-defined context for private data for the
2299:          function evaluation routine (may be `NULL`)

2301:   Calling sequence of `func`:
2302: $    PetscErrorCode func(SNES snes, Vec x, void *ctx);
2303: + snes - the `SNES` solver
2304: . x    - vector to put initial guess
2305: - ctx  - optional user-defined function context

2307:   Level: intermediate

2309: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetFunction()`, `SNESComputeFunction()`, `SNESSetJacobian()`
2310: @*/
2311: PetscErrorCode SNESSetComputeInitialGuess(SNES snes, PetscErrorCode (*func)(SNES snes, Vec x, void *ctx), void *ctx)
2312: {
2313:   PetscFunctionBegin;
2315:   if (func) snes->ops->computeinitialguess = func;
2316:   if (ctx) snes->initialguessP = ctx;
2317:   PetscFunctionReturn(PETSC_SUCCESS);
2318: }

2320: /*@C
2321:   SNESGetRhs - Gets the vector for solving F(x) = `rhs`. If `rhs` is not set
2322:   it assumes a zero right hand side.

2324:   Logically Collective

2326:   Input Parameter:
2327: . snes - the `SNES` context

2329:   Output Parameter:
2330: . rhs - the right hand side vector or `NULL` if the right hand side vector is null

2332:   Level: intermediate

2334: .seealso: [](ch_snes), `SNES`, `SNESGetSolution()`, `SNESGetFunction()`, `SNESComputeFunction()`, `SNESSetJacobian()`, `SNESSetFunction()`
2335: @*/
2336: PetscErrorCode SNESGetRhs(SNES snes, Vec *rhs)
2337: {
2338:   PetscFunctionBegin;
2340:   PetscAssertPointer(rhs, 2);
2341:   *rhs = snes->vec_rhs;
2342:   PetscFunctionReturn(PETSC_SUCCESS);
2343: }

2345: /*@
2346:   SNESComputeFunction - Calls the function that has been set with `SNESSetFunction()`.

2348:   Collective

2350:   Input Parameters:
2351: + snes - the `SNES` context
2352: - x    - input vector

2354:   Output Parameter:
2355: . y - function vector, as set by `SNESSetFunction()`

2357:   Level: developer

2359:   Note:
2360:   `SNESComputeFunction()` is typically used within nonlinear solvers
2361:   implementations, so users would not generally call this routine themselves.

2363: .seealso: [](ch_snes), `SNES`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESComputeMFFunction()`
2364: @*/
2365: PetscErrorCode SNESComputeFunction(SNES snes, Vec x, Vec y)
2366: {
2367:   DM     dm;
2368:   DMSNES sdm;

2370:   PetscFunctionBegin;
2374:   PetscCheckSameComm(snes, 1, x, 2);
2375:   PetscCheckSameComm(snes, 1, y, 3);
2376:   PetscCall(VecValidValues_Internal(x, 2, PETSC_TRUE));

2378:   PetscCall(SNESGetDM(snes, &dm));
2379:   PetscCall(DMGetDMSNES(dm, &sdm));
2380:   PetscCheck(sdm->ops->computefunction || snes->vec_rhs, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetFunction() or SNESSetDM() before SNESComputeFunction(), likely called from SNESSolve().");
2381:   if (sdm->ops->computefunction) {
2382:     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) PetscCall(PetscLogEventBegin(SNES_FunctionEval, snes, x, y, 0));
2383:     PetscCall(VecLockReadPush(x));
2384:     /* ensure domainerror is false prior to computefunction evaluation (may not have been reset) */
2385:     snes->domainerror = PETSC_FALSE;
2386:     {
2387:       void *ctx;
2388:       PetscErrorCode (*computefunction)(SNES, Vec, Vec, void *);
2389:       PetscCall(DMSNESGetFunction(dm, &computefunction, &ctx));
2390:       PetscCallBack("SNES callback function", (*computefunction)(snes, x, y, ctx));
2391:     }
2392:     PetscCall(VecLockReadPop(x));
2393:     if (sdm->ops->computefunction != SNESObjectiveComputeFunctionDefaultFD) PetscCall(PetscLogEventEnd(SNES_FunctionEval, snes, x, y, 0));
2394:   } else /* if (snes->vec_rhs) */ {
2395:     PetscCall(MatMult(snes->jacobian, x, y));
2396:   }
2397:   if (snes->vec_rhs) PetscCall(VecAXPY(y, -1.0, snes->vec_rhs));
2398:   snes->nfuncs++;
2399:   /*
2400:      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
2401:      propagate the value to all processes
2402:   */
2403:   if (snes->domainerror) PetscCall(VecSetInf(y));
2404:   PetscFunctionReturn(PETSC_SUCCESS);
2405: }

2407: /*@
2408:   SNESComputeMFFunction - Calls the function that has been set with `SNESSetMFFunction()`.

2410:   Collective

2412:   Input Parameters:
2413: + snes - the `SNES` context
2414: - x    - input vector

2416:   Output Parameter:
2417: . y - function vector, as set by `SNESSetMFFunction()`

2419:   Level: developer

2421:   Notes:
2422:   `SNESComputeMFFunction()` is used within the matrix vector products called by the matrix created with `MatCreateSNESMF()`
2423:   so users would not generally call this routine themselves.

2425:   Since this function is intended for use with finite differencing it does not subtract the right hand side vector provided with `SNESSolve()`
2426:   while `SNESComputeFunction()` does. As such, this routine cannot be used with  `MatMFFDSetBase()` with a provided F function value even if it applies the
2427:   same function as `SNESComputeFunction()` if a `SNESSolve()` right hand side vector is use because the two functions difference would include this right hand side function.

2429: .seealso: [](ch_snes), `SNES`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESComputeFunction()`, `MatCreateSNESMF`
2430: @*/
2431: PetscErrorCode SNESComputeMFFunction(SNES snes, Vec x, Vec y)
2432: {
2433:   DM     dm;
2434:   DMSNES sdm;

2436:   PetscFunctionBegin;
2440:   PetscCheckSameComm(snes, 1, x, 2);
2441:   PetscCheckSameComm(snes, 1, y, 3);
2442:   PetscCall(VecValidValues_Internal(x, 2, PETSC_TRUE));

2444:   PetscCall(SNESGetDM(snes, &dm));
2445:   PetscCall(DMGetDMSNES(dm, &sdm));
2446:   PetscCall(PetscLogEventBegin(SNES_FunctionEval, snes, x, y, 0));
2447:   PetscCall(VecLockReadPush(x));
2448:   /* ensure domainerror is false prior to computefunction evaluation (may not have been reset) */
2449:   snes->domainerror = PETSC_FALSE;
2450:   PetscCallBack("SNES callback function", (*sdm->ops->computemffunction)(snes, x, y, sdm->mffunctionctx));
2451:   PetscCall(VecLockReadPop(x));
2452:   PetscCall(PetscLogEventEnd(SNES_FunctionEval, snes, x, y, 0));
2453:   snes->nfuncs++;
2454:   /*
2455:      domainerror might not be set on all processes; so we tag vector locally with Inf and the next inner product or norm will
2456:      propagate the value to all processes
2457:   */
2458:   if (snes->domainerror) PetscCall(VecSetInf(y));
2459:   PetscFunctionReturn(PETSC_SUCCESS);
2460: }

2462: /*@
2463:   SNESComputeNGS - Calls the Gauss-Seidel function that has been set with  `SNESSetNGS()`.

2465:   Collective

2467:   Input Parameters:
2468: + snes - the `SNES` context
2469: . x    - input vector
2470: - b    - rhs vector

2472:   Output Parameter:
2473: . x - new solution vector

2475:   Level: developer

2477:   Note:
2478:   `SNESComputeNGS()` is typically used within composed nonlinear solver
2479:   implementations, so most users would not generally call this routine
2480:   themselves.

2482: .seealso: [](ch_snes), `SNESNGS`, `SNESSetNGS()`, `SNESComputeFunction()`
2483: @*/
2484: PetscErrorCode SNESComputeNGS(SNES snes, Vec b, Vec x)
2485: {
2486:   DM     dm;
2487:   DMSNES sdm;

2489:   PetscFunctionBegin;
2493:   PetscCheckSameComm(snes, 1, x, 3);
2494:   if (b) PetscCheckSameComm(snes, 1, b, 2);
2495:   if (b) PetscCall(VecValidValues_Internal(b, 2, PETSC_TRUE));
2496:   PetscCall(PetscLogEventBegin(SNES_NGSEval, snes, x, b, 0));
2497:   PetscCall(SNESGetDM(snes, &dm));
2498:   PetscCall(DMGetDMSNES(dm, &sdm));
2499:   PetscCheck(sdm->ops->computegs, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "Must call SNESSetNGS() before SNESComputeNGS(), likely called from SNESSolve().");
2500:   if (b) PetscCall(VecLockReadPush(b));
2501:   PetscCallBack("SNES callback NGS", (*sdm->ops->computegs)(snes, x, b, sdm->gsctx));
2502:   if (b) PetscCall(VecLockReadPop(b));
2503:   PetscCall(PetscLogEventEnd(SNES_NGSEval, snes, x, b, 0));
2504:   PetscFunctionReturn(PETSC_SUCCESS);
2505: }

2507: PetscErrorCode SNESTestJacobian(SNES snes)
2508: {
2509:   Mat               A, B, C, D, jacobian;
2510:   Vec               x = snes->vec_sol, f = snes->vec_func;
2511:   PetscReal         nrm, gnorm;
2512:   PetscReal         threshold = 1.e-5;
2513:   MatType           mattype;
2514:   PetscInt          m, n, M, N;
2515:   void             *functx;
2516:   PetscBool         complete_print = PETSC_FALSE, threshold_print = PETSC_FALSE, test = PETSC_FALSE, flg, istranspose;
2517:   PetscViewer       viewer, mviewer;
2518:   MPI_Comm          comm;
2519:   PetscInt          tabs;
2520:   static PetscBool  directionsprinted = PETSC_FALSE;
2521:   PetscViewerFormat format;

2523:   PetscFunctionBegin;
2524:   PetscObjectOptionsBegin((PetscObject)snes);
2525:   PetscCall(PetscOptionsName("-snes_test_jacobian", "Compare hand-coded and finite difference Jacobians", "None", &test));
2526:   PetscCall(PetscOptionsReal("-snes_test_jacobian", "Threshold for element difference between hand-coded and finite difference being meaningful", "None", threshold, &threshold, NULL));
2527:   PetscCall(PetscOptionsDeprecated("-snes_test_jacobian_display", "-snes_test_jacobian_view", "3.13", NULL));
2528:   PetscCall(PetscOptionsViewer("-snes_test_jacobian_view", "View difference between hand-coded and finite difference Jacobians element entries", "None", &mviewer, &format, &complete_print));
2529:   PetscCall(PetscOptionsDeprecated("-snes_test_jacobian_display_threshold", "-snes_test_jacobian", "3.13", "-snes_test_jacobian accepts an optional threshold (since v3.10)"));
2530:   /* Cannot remove the what otherwise would be redundant call to (PetscOptionsReal("-snes_test_jacobian_display_threshold") below because its usage is different than the replacement usage */
2531:   PetscCall(PetscOptionsReal("-snes_test_jacobian_display_threshold", "Display difference between hand-coded and finite difference Jacobians which exceed input threshold", "None", threshold, &threshold, &threshold_print));
2532:   PetscOptionsEnd();
2533:   if (!test) PetscFunctionReturn(PETSC_SUCCESS);

2535:   PetscCall(PetscObjectGetComm((PetscObject)snes, &comm));
2536:   PetscCall(PetscViewerASCIIGetStdout(comm, &viewer));
2537:   PetscCall(PetscViewerASCIIGetTab(viewer, &tabs));
2538:   PetscCall(PetscViewerASCIISetTab(viewer, ((PetscObject)snes)->tablevel));
2539:   PetscCall(PetscViewerASCIIPrintf(viewer, "  ---------- Testing Jacobian -------------\n"));
2540:   if (!complete_print && !directionsprinted) {
2541:     PetscCall(PetscViewerASCIIPrintf(viewer, "  Run with -snes_test_jacobian_view and optionally -snes_test_jacobian <threshold> to show difference\n"));
2542:     PetscCall(PetscViewerASCIIPrintf(viewer, "    of hand-coded and finite difference Jacobian entries greater than <threshold>.\n"));
2543:   }
2544:   if (!directionsprinted) {
2545:     PetscCall(PetscViewerASCIIPrintf(viewer, "  Testing hand-coded Jacobian, if (for double precision runs) ||J - Jfd||_F/||J||_F is\n"));
2546:     PetscCall(PetscViewerASCIIPrintf(viewer, "    O(1.e-8), the hand-coded Jacobian is probably correct.\n"));
2547:     directionsprinted = PETSC_TRUE;
2548:   }
2549:   if (complete_print) PetscCall(PetscViewerPushFormat(mviewer, format));

2551:   PetscCall(PetscObjectTypeCompare((PetscObject)snes->jacobian, MATMFFD, &flg));
2552:   if (!flg) jacobian = snes->jacobian;
2553:   else jacobian = snes->jacobian_pre;

2555:   if (!x) {
2556:     PetscCall(MatCreateVecs(jacobian, &x, NULL));
2557:   } else {
2558:     PetscCall(PetscObjectReference((PetscObject)x));
2559:   }
2560:   if (!f) {
2561:     PetscCall(VecDuplicate(x, &f));
2562:   } else {
2563:     PetscCall(PetscObjectReference((PetscObject)f));
2564:   }
2565:   /* evaluate the function at this point because SNESComputeJacobianDefault() assumes that the function has been evaluated and put into snes->vec_func */
2566:   PetscCall(SNESComputeFunction(snes, x, f));
2567:   PetscCall(VecDestroy(&f));
2568:   PetscCall(PetscObjectTypeCompare((PetscObject)snes, SNESKSPTRANSPOSEONLY, &istranspose));
2569:   while (jacobian) {
2570:     Mat JT = NULL, Jsave = NULL;

2572:     if (istranspose) {
2573:       PetscCall(MatCreateTranspose(jacobian, &JT));
2574:       Jsave    = jacobian;
2575:       jacobian = JT;
2576:     }
2577:     PetscCall(PetscObjectBaseTypeCompareAny((PetscObject)jacobian, &flg, MATSEQAIJ, MATMPIAIJ, MATSEQDENSE, MATMPIDENSE, MATSEQBAIJ, MATMPIBAIJ, MATSEQSBAIJ, MATMPISBAIJ, ""));
2578:     if (flg) {
2579:       A = jacobian;
2580:       PetscCall(PetscObjectReference((PetscObject)A));
2581:     } else {
2582:       PetscCall(MatComputeOperator(jacobian, MATAIJ, &A));
2583:     }

2585:     PetscCall(MatGetType(A, &mattype));
2586:     PetscCall(MatGetSize(A, &M, &N));
2587:     PetscCall(MatGetLocalSize(A, &m, &n));
2588:     PetscCall(MatCreate(PetscObjectComm((PetscObject)A), &B));
2589:     PetscCall(MatSetType(B, mattype));
2590:     PetscCall(MatSetSizes(B, m, n, M, N));
2591:     PetscCall(MatSetBlockSizesFromMats(B, A, A));
2592:     PetscCall(MatSetUp(B));
2593:     PetscCall(MatSetOption(B, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE));

2595:     PetscCall(SNESGetFunction(snes, NULL, NULL, &functx));
2596:     PetscCall(SNESComputeJacobianDefault(snes, x, B, B, functx));

2598:     PetscCall(MatDuplicate(B, MAT_COPY_VALUES, &D));
2599:     PetscCall(MatAYPX(D, -1.0, A, DIFFERENT_NONZERO_PATTERN));
2600:     PetscCall(MatNorm(D, NORM_FROBENIUS, &nrm));
2601:     PetscCall(MatNorm(A, NORM_FROBENIUS, &gnorm));
2602:     PetscCall(MatDestroy(&D));
2603:     if (!gnorm) gnorm = 1; /* just in case */
2604:     PetscCall(PetscViewerASCIIPrintf(viewer, "  ||J - Jfd||_F/||J||_F = %g, ||J - Jfd||_F = %g\n", (double)(nrm / gnorm), (double)nrm));

2606:     if (complete_print) {
2607:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Hand-coded Jacobian ----------\n"));
2608:       PetscCall(MatView(A, mviewer));
2609:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Finite difference Jacobian ----------\n"));
2610:       PetscCall(MatView(B, mviewer));
2611:     }

2613:     if (threshold_print || complete_print) {
2614:       PetscInt           Istart, Iend, *ccols, bncols, cncols, j, row;
2615:       PetscScalar       *cvals;
2616:       const PetscInt    *bcols;
2617:       const PetscScalar *bvals;

2619:       PetscCall(MatCreate(PetscObjectComm((PetscObject)A), &C));
2620:       PetscCall(MatSetType(C, mattype));
2621:       PetscCall(MatSetSizes(C, m, n, M, N));
2622:       PetscCall(MatSetBlockSizesFromMats(C, A, A));
2623:       PetscCall(MatSetUp(C));
2624:       PetscCall(MatSetOption(C, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE));

2626:       PetscCall(MatAYPX(B, -1.0, A, DIFFERENT_NONZERO_PATTERN));
2627:       PetscCall(MatGetOwnershipRange(B, &Istart, &Iend));

2629:       for (row = Istart; row < Iend; row++) {
2630:         PetscCall(MatGetRow(B, row, &bncols, &bcols, &bvals));
2631:         PetscCall(PetscMalloc2(bncols, &ccols, bncols, &cvals));
2632:         for (j = 0, cncols = 0; j < bncols; j++) {
2633:           if (PetscAbsScalar(bvals[j]) > threshold) {
2634:             ccols[cncols] = bcols[j];
2635:             cvals[cncols] = bvals[j];
2636:             cncols += 1;
2637:           }
2638:         }
2639:         if (cncols) PetscCall(MatSetValues(C, 1, &row, cncols, ccols, cvals, INSERT_VALUES));
2640:         PetscCall(MatRestoreRow(B, row, &bncols, &bcols, &bvals));
2641:         PetscCall(PetscFree2(ccols, cvals));
2642:       }
2643:       PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
2644:       PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
2645:       PetscCall(PetscViewerASCIIPrintf(viewer, "  Hand-coded minus finite-difference Jacobian with tolerance %g ----------\n", (double)threshold));
2646:       PetscCall(MatView(C, complete_print ? mviewer : viewer));
2647:       PetscCall(MatDestroy(&C));
2648:     }
2649:     PetscCall(MatDestroy(&A));
2650:     PetscCall(MatDestroy(&B));
2651:     PetscCall(MatDestroy(&JT));
2652:     if (Jsave) jacobian = Jsave;
2653:     if (jacobian != snes->jacobian_pre) {
2654:       jacobian = snes->jacobian_pre;
2655:       PetscCall(PetscViewerASCIIPrintf(viewer, "  ---------- Testing Jacobian for preconditioner -------------\n"));
2656:     } else jacobian = NULL;
2657:   }
2658:   PetscCall(VecDestroy(&x));
2659:   if (complete_print) PetscCall(PetscViewerPopFormat(mviewer));
2660:   if (mviewer) PetscCall(PetscViewerDestroy(&mviewer));
2661:   PetscCall(PetscViewerASCIISetTab(viewer, tabs));
2662:   PetscFunctionReturn(PETSC_SUCCESS);
2663: }

2665: /*@
2666:   SNESComputeJacobian - Computes the Jacobian matrix that has been set with `SNESSetJacobian()`.

2668:   Collective

2670:   Input Parameters:
2671: + snes - the `SNES` context
2672: - X    - input vector

2674:   Output Parameters:
2675: + A - Jacobian matrix
2676: - B - optional matrix for building the preconditioner

2678:   Options Database Keys:
2679: + -snes_lag_preconditioner <lag>           - how often to rebuild preconditioner
2680: . -snes_lag_jacobian <lag>                 - how often to rebuild Jacobian
2681: . -snes_test_jacobian <optional threshold> - compare the user provided Jacobian with one compute via finite differences to check for errors.  If a threshold is given, display only those entries whose difference is greater than the threshold.
2682: . -snes_test_jacobian_view                 - display the user provided Jacobian, the finite difference Jacobian and the difference between them to help users detect the location of errors in the user provided Jacobian
2683: . -snes_compare_explicit                   - Compare the computed Jacobian to the finite difference Jacobian and output the differences
2684: . -snes_compare_explicit_draw              - Compare the computed Jacobian to the finite difference Jacobian and draw the result
2685: . -snes_compare_explicit_contour           - Compare the computed Jacobian to the finite difference Jacobian and draw a contour plot with the result
2686: . -snes_compare_operator                   - Make the comparison options above use the operator instead of the preconditioning matrix
2687: . -snes_compare_coloring                   - Compute the finite difference Jacobian using coloring and display norms of difference
2688: . -snes_compare_coloring_display           - Compute the finite difference Jacobian using coloring and display verbose differences
2689: . -snes_compare_coloring_threshold         - Display only those matrix entries that differ by more than a given threshold
2690: . -snes_compare_coloring_threshold_atol    - Absolute tolerance for difference in matrix entries to be displayed by `-snes_compare_coloring_threshold`
2691: . -snes_compare_coloring_threshold_rtol    - Relative tolerance for difference in matrix entries to be displayed by `-snes_compare_coloring_threshold`
2692: . -snes_compare_coloring_draw              - Compute the finite difference Jacobian using coloring and draw differences
2693: - -snes_compare_coloring_draw_contour      - Compute the finite difference Jacobian using coloring and show contours of matrices and differences

2695:   Level: developer

2697:   Note:
2698:   Most users should not need to explicitly call this routine, as it
2699:   is used internally within the nonlinear solvers.

2701:   Developer Notes:
2702:   This has duplicative ways of checking the accuracy of the user provided Jacobian (see the options above). This is for historical reasons, the routine `SNESTestJacobian()` use to used
2703:   for with the `SNESType` of test that has been removed.

2705: .seealso: [](ch_snes), `SNESSetJacobian()`, `KSPSetOperators()`, `MatStructure`, `SNESSetLagPreconditioner()`, `SNESSetLagJacobian()`
2706: @*/
2707: PetscErrorCode SNESComputeJacobian(SNES snes, Vec X, Mat A, Mat B)
2708: {
2709:   PetscBool flag;
2710:   DM        dm;
2711:   DMSNES    sdm;
2712:   KSP       ksp;

2714:   PetscFunctionBegin;
2717:   PetscCheckSameComm(snes, 1, X, 2);
2718:   PetscCall(VecValidValues_Internal(X, 2, PETSC_TRUE));
2719:   PetscCall(SNESGetDM(snes, &dm));
2720:   PetscCall(DMGetDMSNES(dm, &sdm));

2722:   /* make sure that MatAssemblyBegin/End() is called on A matrix if it is matrix-free */
2723:   if (snes->lagjacobian == -2) {
2724:     snes->lagjacobian = -1;

2726:     PetscCall(PetscInfo(snes, "Recomputing Jacobian/preconditioner because lag is -2 (means compute Jacobian, but then never again) \n"));
2727:   } else if (snes->lagjacobian == -1) {
2728:     PetscCall(PetscInfo(snes, "Reusing Jacobian/preconditioner because lag is -1\n"));
2729:     PetscCall(PetscObjectTypeCompare((PetscObject)A, MATMFFD, &flag));
2730:     if (flag) {
2731:       PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
2732:       PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
2733:     }
2734:     PetscFunctionReturn(PETSC_SUCCESS);
2735:   } else if (snes->lagjacobian > 1 && (snes->iter + snes->jac_iter) % snes->lagjacobian) {
2736:     PetscCall(PetscInfo(snes, "Reusing Jacobian/preconditioner because lag is %" PetscInt_FMT " and SNES iteration is %" PetscInt_FMT "\n", snes->lagjacobian, snes->iter));
2737:     PetscCall(PetscObjectTypeCompare((PetscObject)A, MATMFFD, &flag));
2738:     if (flag) {
2739:       PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
2740:       PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
2741:     }
2742:     PetscFunctionReturn(PETSC_SUCCESS);
2743:   }
2744:   if (snes->npc && snes->npcside == PC_LEFT) {
2745:     PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
2746:     PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
2747:     PetscFunctionReturn(PETSC_SUCCESS);
2748:   }

2750:   PetscCall(PetscLogEventBegin(SNES_JacobianEval, snes, X, A, B));
2751:   PetscCall(VecLockReadPush(X));
2752:   {
2753:     void *ctx;
2754:     PetscErrorCode (*J)(SNES, Vec, Mat, Mat, void *);
2755:     PetscCall(DMSNESGetJacobian(dm, &J, &ctx));
2756:     PetscCallBack("SNES callback Jacobian", (*J)(snes, X, A, B, ctx));
2757:   }
2758:   PetscCall(VecLockReadPop(X));
2759:   PetscCall(PetscLogEventEnd(SNES_JacobianEval, snes, X, A, B));

2761:   /* attach latest linearization point to the preconditioning matrix */
2762:   PetscCall(PetscObjectCompose((PetscObject)B, "__SNES_latest_X", (PetscObject)X));

2764:   /* the next line ensures that snes->ksp exists */
2765:   PetscCall(SNESGetKSP(snes, &ksp));
2766:   if (snes->lagpreconditioner == -2) {
2767:     PetscCall(PetscInfo(snes, "Rebuilding preconditioner exactly once since lag is -2\n"));
2768:     PetscCall(KSPSetReusePreconditioner(snes->ksp, PETSC_FALSE));
2769:     snes->lagpreconditioner = -1;
2770:   } else if (snes->lagpreconditioner == -1) {
2771:     PetscCall(PetscInfo(snes, "Reusing preconditioner because lag is -1\n"));
2772:     PetscCall(KSPSetReusePreconditioner(snes->ksp, PETSC_TRUE));
2773:   } else if (snes->lagpreconditioner > 1 && (snes->iter + snes->pre_iter) % snes->lagpreconditioner) {
2774:     PetscCall(PetscInfo(snes, "Reusing preconditioner because lag is %" PetscInt_FMT " and SNES iteration is %" PetscInt_FMT "\n", snes->lagpreconditioner, snes->iter));
2775:     PetscCall(KSPSetReusePreconditioner(snes->ksp, PETSC_TRUE));
2776:   } else {
2777:     PetscCall(PetscInfo(snes, "Rebuilding preconditioner\n"));
2778:     PetscCall(KSPSetReusePreconditioner(snes->ksp, PETSC_FALSE));
2779:   }

2781:   PetscCall(SNESTestJacobian(snes));
2782:   /* make sure user returned a correct Jacobian and preconditioner */
2785:   {
2786:     PetscBool flag = PETSC_FALSE, flag_draw = PETSC_FALSE, flag_contour = PETSC_FALSE, flag_operator = PETSC_FALSE;
2787:     PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_explicit", NULL, NULL, &flag));
2788:     PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_explicit_draw", NULL, NULL, &flag_draw));
2789:     PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_explicit_draw_contour", NULL, NULL, &flag_contour));
2790:     PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_operator", NULL, NULL, &flag_operator));
2791:     if (flag || flag_draw || flag_contour) {
2792:       Mat         Bexp_mine = NULL, Bexp, FDexp;
2793:       PetscViewer vdraw, vstdout;
2794:       PetscBool   flg;
2795:       if (flag_operator) {
2796:         PetscCall(MatComputeOperator(A, MATAIJ, &Bexp_mine));
2797:         Bexp = Bexp_mine;
2798:       } else {
2799:         /* See if the preconditioning matrix can be viewed and added directly */
2800:         PetscCall(PetscObjectBaseTypeCompareAny((PetscObject)B, &flg, MATSEQAIJ, MATMPIAIJ, MATSEQDENSE, MATMPIDENSE, MATSEQBAIJ, MATMPIBAIJ, MATSEQSBAIJ, MATMPIBAIJ, ""));
2801:         if (flg) Bexp = B;
2802:         else {
2803:           /* If the "preconditioning" matrix is itself MATSHELL or some other type without direct support */
2804:           PetscCall(MatComputeOperator(B, MATAIJ, &Bexp_mine));
2805:           Bexp = Bexp_mine;
2806:         }
2807:       }
2808:       PetscCall(MatConvert(Bexp, MATSAME, MAT_INITIAL_MATRIX, &FDexp));
2809:       PetscCall(SNESComputeJacobianDefault(snes, X, FDexp, FDexp, NULL));
2810:       PetscCall(PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes), &vstdout));
2811:       if (flag_draw || flag_contour) {
2812:         PetscCall(PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes), NULL, "Explicit Jacobians", PETSC_DECIDE, PETSC_DECIDE, 300, 300, &vdraw));
2813:         if (flag_contour) PetscCall(PetscViewerPushFormat(vdraw, PETSC_VIEWER_DRAW_CONTOUR));
2814:       } else vdraw = NULL;
2815:       PetscCall(PetscViewerASCIIPrintf(vstdout, "Explicit %s\n", flag_operator ? "Jacobian" : "preconditioning Jacobian"));
2816:       if (flag) PetscCall(MatView(Bexp, vstdout));
2817:       if (vdraw) PetscCall(MatView(Bexp, vdraw));
2818:       PetscCall(PetscViewerASCIIPrintf(vstdout, "Finite difference Jacobian\n"));
2819:       if (flag) PetscCall(MatView(FDexp, vstdout));
2820:       if (vdraw) PetscCall(MatView(FDexp, vdraw));
2821:       PetscCall(MatAYPX(FDexp, -1.0, Bexp, SAME_NONZERO_PATTERN));
2822:       PetscCall(PetscViewerASCIIPrintf(vstdout, "User-provided matrix minus finite difference Jacobian\n"));
2823:       if (flag) PetscCall(MatView(FDexp, vstdout));
2824:       if (vdraw) { /* Always use contour for the difference */
2825:         PetscCall(PetscViewerPushFormat(vdraw, PETSC_VIEWER_DRAW_CONTOUR));
2826:         PetscCall(MatView(FDexp, vdraw));
2827:         PetscCall(PetscViewerPopFormat(vdraw));
2828:       }
2829:       if (flag_contour) PetscCall(PetscViewerPopFormat(vdraw));
2830:       PetscCall(PetscViewerDestroy(&vdraw));
2831:       PetscCall(MatDestroy(&Bexp_mine));
2832:       PetscCall(MatDestroy(&FDexp));
2833:     }
2834:   }
2835:   {
2836:     PetscBool flag = PETSC_FALSE, flag_display = PETSC_FALSE, flag_draw = PETSC_FALSE, flag_contour = PETSC_FALSE, flag_threshold = PETSC_FALSE;
2837:     PetscReal threshold_atol = PETSC_SQRT_MACHINE_EPSILON, threshold_rtol = 10 * PETSC_SQRT_MACHINE_EPSILON;
2838:     PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring", NULL, NULL, &flag));
2839:     PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring_display", NULL, NULL, &flag_display));
2840:     PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring_draw", NULL, NULL, &flag_draw));
2841:     PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring_draw_contour", NULL, NULL, &flag_contour));
2842:     PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring_threshold", NULL, NULL, &flag_threshold));
2843:     if (flag_threshold) {
2844:       PetscCall(PetscOptionsGetReal(((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring_threshold_rtol", &threshold_rtol, NULL));
2845:       PetscCall(PetscOptionsGetReal(((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_compare_coloring_threshold_atol", &threshold_atol, NULL));
2846:     }
2847:     if (flag || flag_display || flag_draw || flag_contour || flag_threshold) {
2848:       Mat           Bfd;
2849:       PetscViewer   vdraw, vstdout;
2850:       MatColoring   coloring;
2851:       ISColoring    iscoloring;
2852:       MatFDColoring matfdcoloring;
2853:       PetscErrorCode (*func)(SNES, Vec, Vec, void *);
2854:       void     *funcctx;
2855:       PetscReal norm1, norm2, normmax;

2857:       PetscCall(MatDuplicate(B, MAT_DO_NOT_COPY_VALUES, &Bfd));
2858:       PetscCall(MatColoringCreate(Bfd, &coloring));
2859:       PetscCall(MatColoringSetType(coloring, MATCOLORINGSL));
2860:       PetscCall(MatColoringSetFromOptions(coloring));
2861:       PetscCall(MatColoringApply(coloring, &iscoloring));
2862:       PetscCall(MatColoringDestroy(&coloring));
2863:       PetscCall(MatFDColoringCreate(Bfd, iscoloring, &matfdcoloring));
2864:       PetscCall(MatFDColoringSetFromOptions(matfdcoloring));
2865:       PetscCall(MatFDColoringSetUp(Bfd, iscoloring, matfdcoloring));
2866:       PetscCall(ISColoringDestroy(&iscoloring));

2868:       /* This method of getting the function is currently unreliable since it doesn't work for DM local functions. */
2869:       PetscCall(SNESGetFunction(snes, NULL, &func, &funcctx));
2870:       PetscCall(MatFDColoringSetFunction(matfdcoloring, (PetscErrorCode(*)(void))func, funcctx));
2871:       PetscCall(PetscObjectSetOptionsPrefix((PetscObject)matfdcoloring, ((PetscObject)snes)->prefix));
2872:       PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)matfdcoloring, "coloring_"));
2873:       PetscCall(MatFDColoringSetFromOptions(matfdcoloring));
2874:       PetscCall(MatFDColoringApply(Bfd, matfdcoloring, X, snes));
2875:       PetscCall(MatFDColoringDestroy(&matfdcoloring));

2877:       PetscCall(PetscViewerASCIIGetStdout(PetscObjectComm((PetscObject)snes), &vstdout));
2878:       if (flag_draw || flag_contour) {
2879:         PetscCall(PetscViewerDrawOpen(PetscObjectComm((PetscObject)snes), NULL, "Colored Jacobians", PETSC_DECIDE, PETSC_DECIDE, 300, 300, &vdraw));
2880:         if (flag_contour) PetscCall(PetscViewerPushFormat(vdraw, PETSC_VIEWER_DRAW_CONTOUR));
2881:       } else vdraw = NULL;
2882:       PetscCall(PetscViewerASCIIPrintf(vstdout, "Explicit preconditioning Jacobian\n"));
2883:       if (flag_display) PetscCall(MatView(B, vstdout));
2884:       if (vdraw) PetscCall(MatView(B, vdraw));
2885:       PetscCall(PetscViewerASCIIPrintf(vstdout, "Colored Finite difference Jacobian\n"));
2886:       if (flag_display) PetscCall(MatView(Bfd, vstdout));
2887:       if (vdraw) PetscCall(MatView(Bfd, vdraw));
2888:       PetscCall(MatAYPX(Bfd, -1.0, B, SAME_NONZERO_PATTERN));
2889:       PetscCall(MatNorm(Bfd, NORM_1, &norm1));
2890:       PetscCall(MatNorm(Bfd, NORM_FROBENIUS, &norm2));
2891:       PetscCall(MatNorm(Bfd, NORM_MAX, &normmax));
2892:       PetscCall(PetscViewerASCIIPrintf(vstdout, "User-provided matrix minus finite difference Jacobian, norm1=%g normFrob=%g normmax=%g\n", (double)norm1, (double)norm2, (double)normmax));
2893:       if (flag_display) PetscCall(MatView(Bfd, vstdout));
2894:       if (vdraw) { /* Always use contour for the difference */
2895:         PetscCall(PetscViewerPushFormat(vdraw, PETSC_VIEWER_DRAW_CONTOUR));
2896:         PetscCall(MatView(Bfd, vdraw));
2897:         PetscCall(PetscViewerPopFormat(vdraw));
2898:       }
2899:       if (flag_contour) PetscCall(PetscViewerPopFormat(vdraw));

2901:       if (flag_threshold) {
2902:         PetscInt bs, rstart, rend, i;
2903:         PetscCall(MatGetBlockSize(B, &bs));
2904:         PetscCall(MatGetOwnershipRange(B, &rstart, &rend));
2905:         for (i = rstart; i < rend; i++) {
2906:           const PetscScalar *ba, *ca;
2907:           const PetscInt    *bj, *cj;
2908:           PetscInt           bn, cn, j, maxentrycol = -1, maxdiffcol = -1, maxrdiffcol = -1;
2909:           PetscReal          maxentry = 0, maxdiff = 0, maxrdiff = 0;
2910:           PetscCall(MatGetRow(B, i, &bn, &bj, &ba));
2911:           PetscCall(MatGetRow(Bfd, i, &cn, &cj, &ca));
2912:           PetscCheck(bn == cn, ((PetscObject)A)->comm, PETSC_ERR_PLIB, "Unexpected different nonzero pattern in -snes_compare_coloring_threshold");
2913:           for (j = 0; j < bn; j++) {
2914:             PetscReal rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol * PetscAbsScalar(ba[j]));
2915:             if (PetscAbsScalar(ba[j]) > PetscAbs(maxentry)) {
2916:               maxentrycol = bj[j];
2917:               maxentry    = PetscRealPart(ba[j]);
2918:             }
2919:             if (PetscAbsScalar(ca[j]) > PetscAbs(maxdiff)) {
2920:               maxdiffcol = bj[j];
2921:               maxdiff    = PetscRealPart(ca[j]);
2922:             }
2923:             if (rdiff > maxrdiff) {
2924:               maxrdiffcol = bj[j];
2925:               maxrdiff    = rdiff;
2926:             }
2927:           }
2928:           if (maxrdiff > 1) {
2929:             PetscCall(PetscViewerASCIIPrintf(vstdout, "row %" PetscInt_FMT " (maxentry=%g at %" PetscInt_FMT ", maxdiff=%g at %" PetscInt_FMT ", maxrdiff=%g at %" PetscInt_FMT "):", i, (double)maxentry, maxentrycol, (double)maxdiff, maxdiffcol, (double)maxrdiff, maxrdiffcol));
2930:             for (j = 0; j < bn; j++) {
2931:               PetscReal rdiff;
2932:               rdiff = PetscAbsScalar(ca[j]) / (threshold_atol + threshold_rtol * PetscAbsScalar(ba[j]));
2933:               if (rdiff > 1) PetscCall(PetscViewerASCIIPrintf(vstdout, " (%" PetscInt_FMT ",%g:%g)", bj[j], (double)PetscRealPart(ba[j]), (double)PetscRealPart(ca[j])));
2934:             }
2935:             PetscCall(PetscViewerASCIIPrintf(vstdout, "\n"));
2936:           }
2937:           PetscCall(MatRestoreRow(B, i, &bn, &bj, &ba));
2938:           PetscCall(MatRestoreRow(Bfd, i, &cn, &cj, &ca));
2939:         }
2940:       }
2941:       PetscCall(PetscViewerDestroy(&vdraw));
2942:       PetscCall(MatDestroy(&Bfd));
2943:     }
2944:   }
2945:   PetscFunctionReturn(PETSC_SUCCESS);
2946: }

2948: /*MC
2949:     SNESJacobianFunction - Function used by `SNES` to compute the nonlinear Jacobian of the function to be solved by `SNES`

2951:      Synopsis:
2952:      #include "petscsnes.h"
2953:      PetscErrorCode SNESJacobianFunction(SNES snes,Vec x,Mat Amat,Mat Pmat,void *ctx);

2955:      Collective

2957:     Input Parameters:
2958: +  x - input vector, the Jacobian is to be computed at this value
2959: -  ctx - [optional] user-defined Jacobian context

2961:     Output Parameters:
2962: +  Amat - the matrix that defines the (approximate) Jacobian
2963: -  Pmat - the matrix to be used in constructing the preconditioner, usually the same as `Amat`.

2965:    Level: intermediate

2967: .seealso: [](ch_snes), `SNES`, `SNESSetFunction()`, `SNESGetFunction()`, `SNESSetJacobian()`, `SNESGetJacobian()`
2968: M*/

2970: /*@C
2971:   SNESSetJacobian - Sets the function to compute Jacobian as well as the
2972:   location to store the matrix.

2974:   Logically Collective

2976:   Input Parameters:
2977: + snes - the `SNES` context
2978: . Amat - the matrix that defines the (approximate) Jacobian
2979: . Pmat - the matrix to be used in constructing the preconditioner, usually the same as `Amat`.
2980: . J    - Jacobian evaluation routine (if `NULL` then `SNES` retains any previously set value), see `SNESJacobianFunction` for details
2981: - ctx  - [optional] user-defined context for private data for the
2982:          Jacobian evaluation routine (may be `NULL`) (if `NULL` then `SNES` retains any previously set value)

2984:   Level: beginner

2986:   Notes:
2987:   If the `Amat` matrix and `Pmat` matrix are different you must call `MatAssemblyBegin()`/`MatAssemblyEnd()` on
2988:   each matrix.

2990:   If you know the operator `Amat` has a null space you can use `MatSetNullSpace()` and `MatSetTransposeNullSpace()` to supply the null
2991:   space to `Amat` and the `KSP` solvers will automatically use that null space as needed during the solution process.

2993:   If using `SNESComputeJacobianDefaultColor()` to assemble a Jacobian, the `ctx` argument
2994:   must be a `MatFDColoring`.

2996:   Other defect-correction schemes can be used by computing a different matrix in place of the Jacobian.  One common
2997:   example is to use the "Picard linearization" which only differentiates through the highest order parts of each term using `SNESSetPicard()`

2999: .seealso: [](ch_snes), `SNES`, `KSPSetOperators()`, `SNESSetFunction()`, `MatMFFDComputeJacobian()`, `SNESComputeJacobianDefaultColor()`, `MatStructure`,
3000:           `SNESSetPicard()`, `SNESJacobianFunction`
3001: @*/
3002: PetscErrorCode SNESSetJacobian(SNES snes, Mat Amat, Mat Pmat, PetscErrorCode (*J)(SNES, Vec, Mat, Mat, void *), void *ctx)
3003: {
3004:   DM dm;

3006:   PetscFunctionBegin;
3010:   if (Amat) PetscCheckSameComm(snes, 1, Amat, 2);
3011:   if (Pmat) PetscCheckSameComm(snes, 1, Pmat, 3);
3012:   PetscCall(SNESGetDM(snes, &dm));
3013:   PetscCall(DMSNESSetJacobian(dm, J, ctx));
3014:   if (Amat) {
3015:     PetscCall(PetscObjectReference((PetscObject)Amat));
3016:     PetscCall(MatDestroy(&snes->jacobian));

3018:     snes->jacobian = Amat;
3019:   }
3020:   if (Pmat) {
3021:     PetscCall(PetscObjectReference((PetscObject)Pmat));
3022:     PetscCall(MatDestroy(&snes->jacobian_pre));

3024:     snes->jacobian_pre = Pmat;
3025:   }
3026:   PetscFunctionReturn(PETSC_SUCCESS);
3027: }

3029: /*@C
3030:   SNESGetJacobian - Returns the Jacobian matrix and optionally the user
3031:   provided context for evaluating the Jacobian.

3033:   Not Collective, but `Mat` object will be parallel if `SNES` object is

3035:   Input Parameter:
3036: . snes - the nonlinear solver context

3038:   Output Parameters:
3039: + Amat - location to stash (approximate) Jacobian matrix (or `NULL`)
3040: . Pmat - location to stash matrix used to compute the preconditioner (or `NULL`)
3041: . J    - location to put Jacobian function (or `NULL`), for calling sequence see `SNESJacobianFunction`
3042: - ctx  - location to stash Jacobian ctx (or `NULL`)

3044:   Level: advanced

3046: .seealso: [](ch_snes), `SNES`, `Mat`, `SNESSetJacobian()`, `SNESComputeJacobian()`, `SNESJacobianFunction`, `SNESGetFunction()`
3047: @*/
3048: PetscErrorCode SNESGetJacobian(SNES snes, Mat *Amat, Mat *Pmat, PetscErrorCode (**J)(SNES, Vec, Mat, Mat, void *), void **ctx)
3049: {
3050:   DM dm;

3052:   PetscFunctionBegin;
3054:   if (Amat) *Amat = snes->jacobian;
3055:   if (Pmat) *Pmat = snes->jacobian_pre;
3056:   PetscCall(SNESGetDM(snes, &dm));
3057:   PetscCall(DMSNESGetJacobian(dm, J, ctx));
3058:   PetscFunctionReturn(PETSC_SUCCESS);
3059: }

3061: static PetscErrorCode SNESSetDefaultComputeJacobian(SNES snes)
3062: {
3063:   DM     dm;
3064:   DMSNES sdm;

3066:   PetscFunctionBegin;
3067:   PetscCall(SNESGetDM(snes, &dm));
3068:   PetscCall(DMGetDMSNES(dm, &sdm));
3069:   if (!sdm->ops->computejacobian && snes->jacobian_pre) {
3070:     DM        dm;
3071:     PetscBool isdense, ismf;

3073:     PetscCall(SNESGetDM(snes, &dm));
3074:     PetscCall(PetscObjectTypeCompareAny((PetscObject)snes->jacobian_pre, &isdense, MATSEQDENSE, MATMPIDENSE, MATDENSE, NULL));
3075:     PetscCall(PetscObjectTypeCompareAny((PetscObject)snes->jacobian_pre, &ismf, MATMFFD, MATSHELL, NULL));
3076:     if (isdense) {
3077:       PetscCall(DMSNESSetJacobian(dm, SNESComputeJacobianDefault, NULL));
3078:     } else if (!ismf) {
3079:       PetscCall(DMSNESSetJacobian(dm, SNESComputeJacobianDefaultColor, NULL));
3080:     }
3081:   }
3082:   PetscFunctionReturn(PETSC_SUCCESS);
3083: }

3085: /*@
3086:   SNESSetUp - Sets up the internal data structures for the later use
3087:   of a nonlinear solver.

3089:   Collective

3091:   Input Parameter:
3092: . snes - the `SNES` context

3094:   Level: advanced

3096:   Note:
3097:   For basic use of the `SNES` solvers the user need not explicitly call
3098:   `SNESSetUp()`, since these actions will automatically occur during
3099:   the call to `SNESSolve()`.  However, if one wishes to control this
3100:   phase separately, `SNESSetUp()` should be called after `SNESCreate()`
3101:   and optional routines of the form SNESSetXXX(), but before `SNESSolve()`.

3103: .seealso: [](ch_snes), `SNES`, `SNESCreate()`, `SNESSolve()`, `SNESDestroy()`
3104: @*/
3105: PetscErrorCode SNESSetUp(SNES snes)
3106: {
3107:   DM             dm;
3108:   DMSNES         sdm;
3109:   SNESLineSearch linesearch, pclinesearch;
3110:   void          *lsprectx, *lspostctx;
3111:   PetscBool      mf_operator, mf;
3112:   Vec            f, fpc;
3113:   void          *funcctx;
3114:   void          *jacctx, *appctx;
3115:   Mat            j, jpre;
3116:   PetscErrorCode (*precheck)(SNESLineSearch, Vec, Vec, PetscBool *, void *);
3117:   PetscErrorCode (*postcheck)(SNESLineSearch, Vec, Vec, Vec, PetscBool *, PetscBool *, void *);
3118:   PetscErrorCode (*func)(SNES, Vec, Vec, void *);
3119:   PetscErrorCode (*jac)(SNES, Vec, Mat, Mat, void *);

3121:   PetscFunctionBegin;
3123:   if (snes->setupcalled) PetscFunctionReturn(PETSC_SUCCESS);
3124:   PetscCall(PetscLogEventBegin(SNES_SetUp, snes, 0, 0, 0));

3126:   if (!((PetscObject)snes)->type_name) PetscCall(SNESSetType(snes, SNESNEWTONLS));

3128:   PetscCall(SNESGetFunction(snes, &snes->vec_func, NULL, NULL));

3130:   PetscCall(SNESGetDM(snes, &dm));
3131:   PetscCall(DMGetDMSNES(dm, &sdm));
3132:   PetscCall(SNESSetDefaultComputeJacobian(snes));

3134:   if (!snes->vec_func) PetscCall(DMCreateGlobalVector(dm, &snes->vec_func));

3136:   if (!snes->ksp) PetscCall(SNESGetKSP(snes, &snes->ksp));

3138:   if (snes->linesearch) {
3139:     PetscCall(SNESGetLineSearch(snes, &snes->linesearch));
3140:     PetscCall(SNESLineSearchSetFunction(snes->linesearch, SNESComputeFunction));
3141:   }

3143:   PetscCall(SNESGetUseMatrixFree(snes, &mf_operator, &mf));
3144:   if (snes->npc && snes->npcside == PC_LEFT) {
3145:     snes->mf          = PETSC_TRUE;
3146:     snes->mf_operator = PETSC_FALSE;
3147:   }

3149:   if (snes->npc) {
3150:     /* copy the DM over */
3151:     PetscCall(SNESGetDM(snes, &dm));
3152:     PetscCall(SNESSetDM(snes->npc, dm));

3154:     PetscCall(SNESGetFunction(snes, &f, &func, &funcctx));
3155:     PetscCall(VecDuplicate(f, &fpc));
3156:     PetscCall(SNESSetFunction(snes->npc, fpc, func, funcctx));
3157:     PetscCall(SNESGetJacobian(snes, &j, &jpre, &jac, &jacctx));
3158:     PetscCall(SNESSetJacobian(snes->npc, j, jpre, jac, jacctx));
3159:     PetscCall(SNESGetApplicationContext(snes, &appctx));
3160:     PetscCall(SNESSetApplicationContext(snes->npc, appctx));
3161:     PetscCall(SNESSetUseMatrixFree(snes->npc, mf_operator, mf));
3162:     PetscCall(VecDestroy(&fpc));

3164:     /* copy the function pointers over */
3165:     PetscCall(PetscObjectCopyFortranFunctionPointers((PetscObject)snes, (PetscObject)snes->npc));

3167:     /* default to 1 iteration */
3168:     PetscCall(SNESSetTolerances(snes->npc, 0.0, 0.0, 0.0, 1, snes->npc->max_funcs));
3169:     if (snes->npcside == PC_RIGHT) {
3170:       PetscCall(SNESSetNormSchedule(snes->npc, SNES_NORM_FINAL_ONLY));
3171:     } else {
3172:       PetscCall(SNESSetNormSchedule(snes->npc, SNES_NORM_NONE));
3173:     }
3174:     PetscCall(SNESSetFromOptions(snes->npc));

3176:     /* copy the line search context over */
3177:     if (snes->linesearch && snes->npc->linesearch) {
3178:       PetscCall(SNESGetLineSearch(snes, &linesearch));
3179:       PetscCall(SNESGetLineSearch(snes->npc, &pclinesearch));
3180:       PetscCall(SNESLineSearchGetPreCheck(linesearch, &precheck, &lsprectx));
3181:       PetscCall(SNESLineSearchGetPostCheck(linesearch, &postcheck, &lspostctx));
3182:       PetscCall(SNESLineSearchSetPreCheck(pclinesearch, precheck, lsprectx));
3183:       PetscCall(SNESLineSearchSetPostCheck(pclinesearch, postcheck, lspostctx));
3184:       PetscCall(PetscObjectCopyFortranFunctionPointers((PetscObject)linesearch, (PetscObject)pclinesearch));
3185:     }
3186:   }
3187:   if (snes->mf) PetscCall(SNESSetUpMatrixFree_Private(snes, snes->mf_operator, snes->mf_version));
3188:   if (snes->ops->usercompute && !snes->user) PetscCall((*snes->ops->usercompute)(snes, (void **)&snes->user));

3190:   snes->jac_iter = 0;
3191:   snes->pre_iter = 0;

3193:   PetscTryTypeMethod(snes, setup);

3195:   PetscCall(SNESSetDefaultComputeJacobian(snes));

3197:   if (snes->npc && snes->npcside == PC_LEFT) {
3198:     if (snes->functype == SNES_FUNCTION_PRECONDITIONED) {
3199:       if (snes->linesearch) {
3200:         PetscCall(SNESGetLineSearch(snes, &linesearch));
3201:         PetscCall(SNESLineSearchSetFunction(linesearch, SNESComputeFunctionDefaultNPC));
3202:       }
3203:     }
3204:   }
3205:   PetscCall(PetscLogEventEnd(SNES_SetUp, snes, 0, 0, 0));
3206:   snes->setupcalled = PETSC_TRUE;
3207:   PetscFunctionReturn(PETSC_SUCCESS);
3208: }

3210: /*@
3211:   SNESReset - Resets a `SNES` context to the snessetupcalled = 0 state and removes any allocated `Vec`s and `Mat`s

3213:   Collective

3215:   Input Parameter:
3216: . snes - iterative context obtained from `SNESCreate()`

3218:   Level: intermediate

3220:   Notes:
3221:   Call this if you wish to reuse a `SNES` but with different size vectors

3223:   Also calls the application context destroy routine set with `SNESSetComputeApplicationContext()`

3225: .seealso: [](ch_snes), `SNES`, `SNESDestroy()`, `SNESCreate()`, `SNESSetUp()`, `SNESSolve()`
3226: @*/
3227: PetscErrorCode SNESReset(SNES snes)
3228: {
3229:   PetscFunctionBegin;
3231:   if (snes->ops->userdestroy && snes->user) {
3232:     PetscCall((*snes->ops->userdestroy)((void **)&snes->user));
3233:     snes->user = NULL;
3234:   }
3235:   if (snes->npc) PetscCall(SNESReset(snes->npc));

3237:   PetscTryTypeMethod(snes, reset);
3238:   if (snes->ksp) PetscCall(KSPReset(snes->ksp));

3240:   if (snes->linesearch) PetscCall(SNESLineSearchReset(snes->linesearch));

3242:   PetscCall(VecDestroy(&snes->vec_rhs));
3243:   PetscCall(VecDestroy(&snes->vec_sol));
3244:   PetscCall(VecDestroy(&snes->vec_sol_update));
3245:   PetscCall(VecDestroy(&snes->vec_func));
3246:   PetscCall(MatDestroy(&snes->jacobian));
3247:   PetscCall(MatDestroy(&snes->jacobian_pre));
3248:   PetscCall(MatDestroy(&snes->picard));
3249:   PetscCall(VecDestroyVecs(snes->nwork, &snes->work));
3250:   PetscCall(VecDestroyVecs(snes->nvwork, &snes->vwork));

3252:   snes->alwayscomputesfinalresidual = PETSC_FALSE;

3254:   snes->nwork = snes->nvwork = 0;
3255:   snes->setupcalled          = PETSC_FALSE;
3256:   PetscFunctionReturn(PETSC_SUCCESS);
3257: }

3259: /*@
3260:   SNESConvergedReasonViewCancel - Clears all the reason view functions for a `SNES` object.

3262:   Collective

3264:   Input Parameter:
3265: . snes - iterative context obtained from `SNESCreate()`

3267:   Level: intermediate

3269: .seealso: [](ch_snes), `SNES`, `SNESCreate()`, `SNESDestroy()`, `SNESReset()`
3270: @*/
3271: PetscErrorCode SNESConvergedReasonViewCancel(SNES snes)
3272: {
3273:   PetscInt i;

3275:   PetscFunctionBegin;
3277:   for (i = 0; i < snes->numberreasonviews; i++) {
3278:     if (snes->reasonviewdestroy[i]) PetscCall((*snes->reasonviewdestroy[i])(&snes->reasonviewcontext[i]));
3279:   }
3280:   snes->numberreasonviews = 0;
3281:   PetscFunctionReturn(PETSC_SUCCESS);
3282: }

3284: /*@C
3285:   SNESDestroy - Destroys the nonlinear solver context that was created
3286:   with `SNESCreate()`.

3288:   Collective

3290:   Input Parameter:
3291: . snes - the `SNES` context

3293:   Level: beginner

3295: .seealso: [](ch_snes), `SNES`, `SNESCreate()`, `SNESSolve()`
3296: @*/
3297: PetscErrorCode SNESDestroy(SNES *snes)
3298: {
3299:   PetscFunctionBegin;
3300:   if (!*snes) PetscFunctionReturn(PETSC_SUCCESS);
3302:   if (--((PetscObject)(*snes))->refct > 0) {
3303:     *snes = NULL;
3304:     PetscFunctionReturn(PETSC_SUCCESS);
3305:   }

3307:   PetscCall(SNESReset((*snes)));
3308:   PetscCall(SNESDestroy(&(*snes)->npc));

3310:   /* if memory was published with SAWs then destroy it */
3311:   PetscCall(PetscObjectSAWsViewOff((PetscObject)*snes));
3312:   PetscTryTypeMethod((*snes), destroy);

3314:   if ((*snes)->dm) PetscCall(DMCoarsenHookRemove((*snes)->dm, DMCoarsenHook_SNESVecSol, DMRestrictHook_SNESVecSol, *snes));
3315:   PetscCall(DMDestroy(&(*snes)->dm));
3316:   PetscCall(KSPDestroy(&(*snes)->ksp));
3317:   PetscCall(SNESLineSearchDestroy(&(*snes)->linesearch));

3319:   PetscCall(PetscFree((*snes)->kspconvctx));
3320:   if ((*snes)->ops->convergeddestroy) PetscCall((*(*snes)->ops->convergeddestroy)((*snes)->cnvP));
3321:   if ((*snes)->conv_hist_alloc) PetscCall(PetscFree2((*snes)->conv_hist, (*snes)->conv_hist_its));
3322:   PetscCall(SNESMonitorCancel((*snes)));
3323:   PetscCall(SNESConvergedReasonViewCancel((*snes)));
3324:   PetscCall(PetscHeaderDestroy(snes));
3325:   PetscFunctionReturn(PETSC_SUCCESS);
3326: }

3328: /* ----------- Routines to set solver parameters ---------- */

3330: /*@
3331:   SNESSetLagPreconditioner - Determines when the preconditioner is rebuilt in the nonlinear solve.

3333:   Logically Collective

3335:   Input Parameters:
3336: + snes - the `SNES` context
3337: - lag  - 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3338:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

3340:   Options Database Keys:
3341: + -snes_lag_jacobian_persists <true,false>       - sets the persistence through multiple SNES solves
3342: . -snes_lag_jacobian <-2,1,2,...>                - sets the lag
3343: . -snes_lag_preconditioner_persists <true,false> - sets the persistence through multiple SNES solves
3344: - -snes_lag_preconditioner <-2,1,2,...>          - sets the lag

3346:   Notes:

3348:   Level: intermediate

3350:    The default is 1
3351:    The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1 or `SNESSetLagPreconditionerPersists()` was called

3353:    `SNESSetLagPreconditionerPersists()` allows using the same uniform lagging (for example every second linear solve) across multiple nonlinear solves.

3355: .seealso: [](ch_snes), `SNESSetTrustRegionTolerance()`, `SNESGetLagPreconditioner()`, `SNESSetLagJacobian()`, `SNESGetLagJacobian()`, `SNESSetLagPreconditionerPersists()`,
3356:           `SNESSetLagJacobianPersists()`, `SNES`, `SNESSolve()`
3357: @*/
3358: PetscErrorCode SNESSetLagPreconditioner(SNES snes, PetscInt lag)
3359: {
3360:   PetscFunctionBegin;
3362:   PetscCheck(lag >= -2, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Lag must be -2, -1, 1 or greater");
3363:   PetscCheck(lag, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Lag cannot be 0");
3365:   snes->lagpreconditioner = lag;
3366:   PetscFunctionReturn(PETSC_SUCCESS);
3367: }

3369: /*@
3370:   SNESSetGridSequence - sets the number of steps of grid sequencing that `SNES` will do

3372:   Logically Collective

3374:   Input Parameters:
3375: + snes  - the `SNES` context
3376: - steps - the number of refinements to do, defaults to 0

3378:   Options Database Key:
3379: . -snes_grid_sequence <steps> - Use grid sequencing to generate initial guess

3381:   Level: intermediate

3383:   Note:
3384:   Use `SNESGetSolution()` to extract the fine grid solution after grid sequencing.

3386: .seealso: [](ch_snes), `SNES`, `SNESSetTrustRegionTolerance()`, `SNESGetLagPreconditioner()`, `SNESSetLagJacobian()`, `SNESGetLagJacobian()`, `SNESGetGridSequence()`
3387: @*/
3388: PetscErrorCode SNESSetGridSequence(SNES snes, PetscInt steps)
3389: {
3390:   PetscFunctionBegin;
3393:   snes->gridsequence = steps;
3394:   PetscFunctionReturn(PETSC_SUCCESS);
3395: }

3397: /*@
3398:   SNESGetGridSequence - gets the number of steps of grid sequencing that `SNES` will do

3400:   Logically Collective

3402:   Input Parameter:
3403: . snes - the `SNES` context

3405:   Output Parameter:
3406: . steps - the number of refinements to do, defaults to 0

3408:   Options Database Key:
3409: . -snes_grid_sequence <steps> - set number of refinements

3411:   Level: intermediate

3413:   Note:
3414:   Use `SNESGetSolution()` to extract the fine grid solution after grid sequencing.

3416: .seealso: [](ch_snes), `SNESSetTrustRegionTolerance()`, `SNESGetLagPreconditioner()`, `SNESSetLagJacobian()`, `SNESGetLagJacobian()`, `SNESSetGridSequence()`
3417: @*/
3418: PetscErrorCode SNESGetGridSequence(SNES snes, PetscInt *steps)
3419: {
3420:   PetscFunctionBegin;
3422:   *steps = snes->gridsequence;
3423:   PetscFunctionReturn(PETSC_SUCCESS);
3424: }

3426: /*@
3427:   SNESGetLagPreconditioner - Return how often the preconditioner is rebuilt

3429:   Not Collective

3431:   Input Parameter:
3432: . snes - the `SNES` context

3434:   Output Parameter:
3435: . lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3436:          the Jacobian is built etc. -2 indicates rebuild preconditioner at next chance but then never rebuild after that

3438:   Options Database Keys:
3439: + -snes_lag_jacobian_persists <true,false>       - sets the persistence through multiple SNES solves
3440: . -snes_lag_jacobian <-2,1,2,...>                - sets the lag
3441: . -snes_lag_preconditioner_persists <true,false> - sets the persistence through multiple SNES solves
3442: - -snes_lag_preconditioner <-2,1,2,...>          - sets the lag

3444:   Level: intermediate

3446:   Notes:
3447:   The default is 1

3449:   The preconditioner is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1

3451: .seealso: [](ch_snes), `SNES`, `SNESSetTrustRegionTolerance()`, `SNESSetLagPreconditioner()`, `SNESSetLagJacobianPersists()`, `SNESSetLagPreconditionerPersists()`
3452: @*/
3453: PetscErrorCode SNESGetLagPreconditioner(SNES snes, PetscInt *lag)
3454: {
3455:   PetscFunctionBegin;
3457:   *lag = snes->lagpreconditioner;
3458:   PetscFunctionReturn(PETSC_SUCCESS);
3459: }

3461: /*@
3462:   SNESSetLagJacobian - Set when the Jacobian is rebuilt in the nonlinear solve. See `SNESSetLagPreconditioner()` for determining how
3463:   often the preconditioner is rebuilt.

3465:   Logically Collective

3467:   Input Parameters:
3468: + snes - the `SNES` context
3469: - lag  - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3470:          the Jacobian is built etc. -2 means rebuild at next chance but then never again

3472:   Options Database Keys:
3473: + -snes_lag_jacobian_persists <true,false>       - sets the persistence through multiple SNES solves
3474: . -snes_lag_jacobian <-2,1,2,...>                - sets the lag
3475: . -snes_lag_preconditioner_persists <true,false> - sets the persistence through multiple SNES solves
3476: - -snes_lag_preconditioner <-2,1,2,...>          - sets the lag.

3478:   Level: intermediate

3480:   Notes:
3481:   The default is 1

3483:   The Jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1

3485:   If  -1 is used before the very first nonlinear solve the CODE WILL FAIL! because no Jacobian is used, use -2 to indicate you want it recomputed
3486:   at the next Newton step but never again (unless it is reset to another value)

3488: .seealso: [](ch_snes), `SNES`, `SNESSetTrustRegionTolerance()`, `SNESGetLagPreconditioner()`, `SNESSetLagPreconditioner()`, `SNESGetLagJacobianPersists()`, `SNESSetLagPreconditionerPersists()`
3489: @*/
3490: PetscErrorCode SNESSetLagJacobian(SNES snes, PetscInt lag)
3491: {
3492:   PetscFunctionBegin;
3494:   PetscCheck(lag >= -2, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Lag must be -2, -1, 1 or greater");
3495:   PetscCheck(lag, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Lag cannot be 0");
3497:   snes->lagjacobian = lag;
3498:   PetscFunctionReturn(PETSC_SUCCESS);
3499: }

3501: /*@
3502:   SNESGetLagJacobian - Get how often the Jacobian is rebuilt. See `SNESGetLagPreconditioner()` to determine when the preconditioner is rebuilt

3504:   Not Collective

3506:   Input Parameter:
3507: . snes - the `SNES` context

3509:   Output Parameter:
3510: . lag - -1 indicates NEVER rebuild, 1 means rebuild every time the Jacobian is computed within a single nonlinear solve, 2 means every second time
3511:          the Jacobian is built etc.

3513:   Level: intermediate

3515:   Notes:
3516:   The default is 1

3518:   The jacobian is ALWAYS built in the first iteration of a nonlinear solve unless lag is -1 or `SNESSetLagJacobianPersists()` was called.

3520: .seealso: [](ch_snes), `SNES`, `SNESSetTrustRegionTolerance()`, `SNESSetLagJacobian()`, `SNESSetLagPreconditioner()`, `SNESGetLagPreconditioner()`, `SNESSetLagJacobianPersists()`, `SNESSetLagPreconditionerPersists()`

3522: @*/
3523: PetscErrorCode SNESGetLagJacobian(SNES snes, PetscInt *lag)
3524: {
3525:   PetscFunctionBegin;
3527:   *lag = snes->lagjacobian;
3528:   PetscFunctionReturn(PETSC_SUCCESS);
3529: }

3531: /*@
3532:   SNESSetLagJacobianPersists - Set whether or not the Jacobian lagging persists through multiple nonlinear solves

3534:   Logically collective

3536:   Input Parameters:
3537: + snes - the `SNES` context
3538: - flg  - jacobian lagging persists if true

3540:   Options Database Keys:
3541: + -snes_lag_jacobian_persists <true,false>       - sets the persistence through multiple SNES solves
3542: . -snes_lag_jacobian <-2,1,2,...>                - sets the lag
3543: . -snes_lag_preconditioner_persists <true,false> - sets the persistence through multiple SNES solves
3544: - -snes_lag_preconditioner <-2,1,2,...>          - sets the lag

3546:   Level: advanced

3548:   Notes:
3549:   Normally when `SNESSetLagJacobian()` is used, the Jacobian is always rebuilt at the beginning of each new nonlinear solve, this removes that.

3551:   This is useful both for nonlinear preconditioning, where it's appropriate to have the Jacobian be stale by
3552:   several solves, and for implicit time-stepping, where Jacobian lagging in the inner nonlinear solve over several
3553:   timesteps may present huge efficiency gains.

3555: .seealso: [](ch_snes), `SNES`, `SNESSetLagPreconditionerPersists()`, `SNESSetLagJacobian()`, `SNESGetLagJacobian()`, `SNESGetNPC()`
3556: @*/
3557: PetscErrorCode SNESSetLagJacobianPersists(SNES snes, PetscBool flg)
3558: {
3559:   PetscFunctionBegin;
3562:   snes->lagjac_persist = flg;
3563:   PetscFunctionReturn(PETSC_SUCCESS);
3564: }

3566: /*@
3567:   SNESSetLagPreconditionerPersists - Set whether or not the preconditioner lagging persists through multiple nonlinear solves

3569:   Logically Collective

3571:   Input Parameters:
3572: + snes - the `SNES` context
3573: - flg  - preconditioner lagging persists if true

3575:   Options Database Keys:
3576: + -snes_lag_jacobian_persists <true,false>       - sets the persistence through multiple SNES solves
3577: . -snes_lag_jacobian <-2,1,2,...>                - sets the lag
3578: . -snes_lag_preconditioner_persists <true,false> - sets the persistence through multiple SNES solves
3579: - -snes_lag_preconditioner <-2,1,2,...>          - sets the lag

3581:   Level: developer

3583:   Notes:
3584:   Normally when `SNESSetLagPreconditioner()` is used, the preconditioner is always rebuilt at the beginning of each new nonlinear solve, this removes that.

3586:   This is useful both for nonlinear preconditioning, where it's appropriate to have the preconditioner be stale
3587:   by several solves, and for implicit time-stepping, where preconditioner lagging in the inner nonlinear solve over
3588:   several timesteps may present huge efficiency gains.

3590: .seealso: [](ch_snes), `SNES`, `SNESSetLagJacobianPersists()`, `SNESSetLagJacobian()`, `SNESGetLagJacobian()`, `SNESGetNPC()`, `SNESSetLagPreconditioner()`
3591: @*/
3592: PetscErrorCode SNESSetLagPreconditionerPersists(SNES snes, PetscBool flg)
3593: {
3594:   PetscFunctionBegin;
3597:   snes->lagpre_persist = flg;
3598:   PetscFunctionReturn(PETSC_SUCCESS);
3599: }

3601: /*@
3602:   SNESSetForceIteration - force `SNESSolve()` to take at least one iteration regardless of the initial residual norm

3604:   Logically Collective

3606:   Input Parameters:
3607: + snes  - the `SNES` context
3608: - force - `PETSC_TRUE` require at least one iteration

3610:   Options Database Key:
3611: . -snes_force_iteration <force> - Sets forcing an iteration

3613:   Level: intermediate

3615:   Note:
3616:   This is used sometimes with `TS` to prevent `TS` from detecting a false steady state solution

3618: .seealso: [](ch_snes), `SNES`, `TS`, `SNESSetTrustRegionTolerance()`, `SNESSetDivergenceTolerance()`
3619: @*/
3620: PetscErrorCode SNESSetForceIteration(SNES snes, PetscBool force)
3621: {
3622:   PetscFunctionBegin;
3624:   snes->forceiteration = force;
3625:   PetscFunctionReturn(PETSC_SUCCESS);
3626: }

3628: /*@
3629:   SNESGetForceIteration - Check whether or not `SNESSolve()` take at least one iteration regardless of the initial residual norm

3631:   Logically Collective

3633:   Input Parameter:
3634: . snes - the `SNES` context

3636:   Output Parameter:
3637: . force - `PETSC_TRUE` requires at least one iteration.

3639:   Level: intermediate

3641: .seealso: [](ch_snes), `SNES`, `SNESSetForceIteration()`, `SNESSetTrustRegionTolerance()`, `SNESSetDivergenceTolerance()`
3642: @*/
3643: PetscErrorCode SNESGetForceIteration(SNES snes, PetscBool *force)
3644: {
3645:   PetscFunctionBegin;
3647:   *force = snes->forceiteration;
3648:   PetscFunctionReturn(PETSC_SUCCESS);
3649: }

3651: /*@
3652:   SNESSetTolerances - Sets `SNES` various parameters used in convergence tests.

3654:   Logically Collective

3656:   Input Parameters:
3657: + snes   - the `SNES` context
3658: . abstol - absolute convergence tolerance
3659: . rtol   - relative convergence tolerance
3660: . stol   - convergence tolerance in terms of the norm of the change in the solution between steps,  || delta x || < stol*|| x ||
3661: . maxit  - maximum number of iterations, default 50.
3662: - maxf   - maximum number of function evaluations (-1 indicates no limit), default 1000

3664:   Options Database Keys:
3665: + -snes_atol <abstol>    - Sets abstol
3666: . -snes_rtol <rtol>      - Sets rtol
3667: . -snes_stol <stol>      - Sets stol
3668: . -snes_max_it <maxit>   - Sets maxit
3669: - -snes_max_funcs <maxf> - Sets maxf

3671:   Level: intermediate

3673: .seealso: [](ch_snes), `SNESolve()`, `SNES`, `SNESSetTrustRegionTolerance()`, `SNESSetDivergenceTolerance()`, `SNESSetForceIteration()`
3674: @*/
3675: PetscErrorCode SNESSetTolerances(SNES snes, PetscReal abstol, PetscReal rtol, PetscReal stol, PetscInt maxit, PetscInt maxf)
3676: {
3677:   PetscFunctionBegin;

3685:   if (abstol != (PetscReal)PETSC_DEFAULT) {
3686:     PetscCheck(abstol >= 0.0, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Absolute tolerance %g must be non-negative", (double)abstol);
3687:     snes->abstol = abstol;
3688:   }
3689:   if (rtol != (PetscReal)PETSC_DEFAULT) {
3690:     PetscCheck(rtol >= 0.0 && 1.0 > rtol, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Relative tolerance %g must be non-negative and less than 1.0", (double)rtol);
3691:     snes->rtol = rtol;
3692:   }
3693:   if (stol != (PetscReal)PETSC_DEFAULT) {
3694:     PetscCheck(stol >= 0.0, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Step tolerance %g must be non-negative", (double)stol);
3695:     snes->stol = stol;
3696:   }
3697:   if (maxit != PETSC_DEFAULT) {
3698:     PetscCheck(maxit >= 0, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Maximum number of iterations %" PetscInt_FMT " must be non-negative", maxit);
3699:     snes->max_its = maxit;
3700:   }
3701:   if (maxf != PETSC_DEFAULT) {
3702:     PetscCheck(maxf >= -1, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_OUTOFRANGE, "Maximum number of function evaluations %" PetscInt_FMT " must be -1 or nonnegative", maxf);
3703:     snes->max_funcs = maxf;
3704:   }
3705:   snes->tolerancesset = PETSC_TRUE;
3706:   PetscFunctionReturn(PETSC_SUCCESS);
3707: }

3709: /*@
3710:   SNESSetDivergenceTolerance - Sets the divergence tolerance used for the `SNES` divergence test.

3712:   Logically Collective

3714:   Input Parameters:
3715: + snes   - the `SNES` context
3716: - divtol - the divergence tolerance. Use -1 to deactivate the test, default is 1e4

3718:   Options Database Key:
3719: . -snes_divergence_tolerance <divtol> - Sets `divtol`

3721:   Level: intermediate

3723: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetTolerances()`, `SNESGetDivergenceTolerance`
3724: @*/
3725: PetscErrorCode SNESSetDivergenceTolerance(SNES snes, PetscReal divtol)
3726: {
3727:   PetscFunctionBegin;

3731:   if (divtol != (PetscReal)PETSC_DEFAULT) {
3732:     snes->divtol = divtol;
3733:   } else {
3734:     snes->divtol = 1.0e4;
3735:   }
3736:   PetscFunctionReturn(PETSC_SUCCESS);
3737: }

3739: /*@
3740:   SNESGetTolerances - Gets various parameters used in convergence tests.

3742:   Not Collective

3744:   Input Parameters:
3745: + snes  - the `SNES` context
3746: . atol  - absolute convergence tolerance
3747: . rtol  - relative convergence tolerance
3748: . stol  - convergence tolerance in terms of the norm
3749:            of the change in the solution between steps
3750: . maxit - maximum number of iterations
3751: - maxf  - maximum number of function evaluations

3753:   Level: intermediate

3755:   Note:
3756:   The user can specify `NULL` for any parameter that is not needed.

3758: .seealso: [](ch_snes), `SNES`, `SNESSetTolerances()`
3759: @*/
3760: PetscErrorCode SNESGetTolerances(SNES snes, PetscReal *atol, PetscReal *rtol, PetscReal *stol, PetscInt *maxit, PetscInt *maxf)
3761: {
3762:   PetscFunctionBegin;
3764:   if (atol) *atol = snes->abstol;
3765:   if (rtol) *rtol = snes->rtol;
3766:   if (stol) *stol = snes->stol;
3767:   if (maxit) *maxit = snes->max_its;
3768:   if (maxf) *maxf = snes->max_funcs;
3769:   PetscFunctionReturn(PETSC_SUCCESS);
3770: }

3772: /*@
3773:   SNESGetDivergenceTolerance - Gets divergence tolerance used in divergence test.

3775:   Not Collective

3777:   Input Parameters:
3778: + snes   - the `SNES` context
3779: - divtol - divergence tolerance

3781:   Level: intermediate

3783: .seealso: [](ch_snes), `SNES`, `SNESSetDivergenceTolerance()`
3784: @*/
3785: PetscErrorCode SNESGetDivergenceTolerance(SNES snes, PetscReal *divtol)
3786: {
3787:   PetscFunctionBegin;
3789:   if (divtol) *divtol = snes->divtol;
3790:   PetscFunctionReturn(PETSC_SUCCESS);
3791: }

3793: /*@
3794:   SNESSetTrustRegionTolerance - Sets the trust region parameter tolerance.

3796:   Logically Collective

3798:   Input Parameters:
3799: + snes - the `SNES` context
3800: - tol  - tolerance

3802:   Options Database Key:
3803: . -snes_tr_tol <tol> - Sets tol

3805:   Level: intermediate

3807: .seealso: [](ch_snes), `SNES`, `SNESNEWTONTR`, `SNESSetTolerances()`
3808: @*/
3809: PetscErrorCode SNESSetTrustRegionTolerance(SNES snes, PetscReal tol)
3810: {
3811:   PetscFunctionBegin;
3814:   snes->deltatol = tol;
3815:   PetscFunctionReturn(PETSC_SUCCESS);
3816: }

3818: PETSC_INTERN PetscErrorCode SNESMonitorRange_Private(SNES, PetscInt, PetscReal *);

3820: PetscErrorCode SNESMonitorLGRange(SNES snes, PetscInt n, PetscReal rnorm, void *monctx)
3821: {
3822:   PetscDrawLG      lg;
3823:   PetscReal        x, y, per;
3824:   PetscViewer      v = (PetscViewer)monctx;
3825:   static PetscReal prev; /* should be in the context */
3826:   PetscDraw        draw;

3828:   PetscFunctionBegin;
3830:   PetscCall(PetscViewerDrawGetDrawLG(v, 0, &lg));
3831:   if (!n) PetscCall(PetscDrawLGReset(lg));
3832:   PetscCall(PetscDrawLGGetDraw(lg, &draw));
3833:   PetscCall(PetscDrawSetTitle(draw, "Residual norm"));
3834:   x = (PetscReal)n;
3835:   if (rnorm > 0.0) y = PetscLog10Real(rnorm);
3836:   else y = -15.0;
3837:   PetscCall(PetscDrawLGAddPoint(lg, &x, &y));
3838:   if (n < 20 || !(n % 5) || snes->reason) {
3839:     PetscCall(PetscDrawLGDraw(lg));
3840:     PetscCall(PetscDrawLGSave(lg));
3841:   }

3843:   PetscCall(PetscViewerDrawGetDrawLG(v, 1, &lg));
3844:   if (!n) PetscCall(PetscDrawLGReset(lg));
3845:   PetscCall(PetscDrawLGGetDraw(lg, &draw));
3846:   PetscCall(PetscDrawSetTitle(draw, "% elements > .2*max element"));
3847:   PetscCall(SNESMonitorRange_Private(snes, n, &per));
3848:   x = (PetscReal)n;
3849:   y = 100.0 * per;
3850:   PetscCall(PetscDrawLGAddPoint(lg, &x, &y));
3851:   if (n < 20 || !(n % 5) || snes->reason) {
3852:     PetscCall(PetscDrawLGDraw(lg));
3853:     PetscCall(PetscDrawLGSave(lg));
3854:   }

3856:   PetscCall(PetscViewerDrawGetDrawLG(v, 2, &lg));
3857:   if (!n) {
3858:     prev = rnorm;
3859:     PetscCall(PetscDrawLGReset(lg));
3860:   }
3861:   PetscCall(PetscDrawLGGetDraw(lg, &draw));
3862:   PetscCall(PetscDrawSetTitle(draw, "(norm -oldnorm)/oldnorm"));
3863:   x = (PetscReal)n;
3864:   y = (prev - rnorm) / prev;
3865:   PetscCall(PetscDrawLGAddPoint(lg, &x, &y));
3866:   if (n < 20 || !(n % 5) || snes->reason) {
3867:     PetscCall(PetscDrawLGDraw(lg));
3868:     PetscCall(PetscDrawLGSave(lg));
3869:   }

3871:   PetscCall(PetscViewerDrawGetDrawLG(v, 3, &lg));
3872:   if (!n) PetscCall(PetscDrawLGReset(lg));
3873:   PetscCall(PetscDrawLGGetDraw(lg, &draw));
3874:   PetscCall(PetscDrawSetTitle(draw, "(norm -oldnorm)/oldnorm*(% > .2 max)"));
3875:   x = (PetscReal)n;
3876:   y = (prev - rnorm) / (prev * per);
3877:   if (n > 2) { /*skip initial crazy value */
3878:     PetscCall(PetscDrawLGAddPoint(lg, &x, &y));
3879:   }
3880:   if (n < 20 || !(n % 5) || snes->reason) {
3881:     PetscCall(PetscDrawLGDraw(lg));
3882:     PetscCall(PetscDrawLGSave(lg));
3883:   }
3884:   prev = rnorm;
3885:   PetscFunctionReturn(PETSC_SUCCESS);
3886: }

3888: /*@
3889:   SNESConverged - Run the convergence test and update the `SNESConvergedReason`.

3891:   Collective

3893:   Input Parameters:
3894: + snes  - the `SNES` context
3895: . it    - current iteration
3896: . xnorm - 2-norm of current iterate
3897: . snorm - 2-norm of current step
3898: - fnorm - 2-norm of function

3900:   Level: developer

3902:   Note:
3903:   This routine is called by the `SNES` implementations.
3904:   It does not typically need to be called by the user.

3906: .seealso: [](ch_snes), `SNES`, `SNESSolve`, `SNESSetConvergenceTest()`, `SNESGetConvergenceTest()`
3907: @*/
3908: PetscErrorCode SNESConverged(SNES snes, PetscInt it, PetscReal xnorm, PetscReal snorm, PetscReal fnorm)
3909: {
3910:   PetscFunctionBegin;
3911:   if (!snes->reason) {
3912:     if (snes->normschedule == SNES_NORM_ALWAYS) PetscUseTypeMethod(snes, converged, it, xnorm, snorm, fnorm, &snes->reason, snes->cnvP);
3913:     if (it == snes->max_its && !snes->reason) {
3914:       if (snes->normschedule == SNES_NORM_ALWAYS) {
3915:         PetscCall(PetscInfo(snes, "Maximum number of iterations has been reached: %" PetscInt_FMT "\n", snes->max_its));
3916:         snes->reason = SNES_DIVERGED_MAX_IT;
3917:       } else snes->reason = SNES_CONVERGED_ITS;
3918:     }
3919:   }
3920:   PetscFunctionReturn(PETSC_SUCCESS);
3921: }

3923: /*@
3924:   SNESMonitor - runs the user provided monitor routines, if they exist

3926:   Collective

3928:   Input Parameters:
3929: + snes  - nonlinear solver context obtained from `SNESCreate()`
3930: . iter  - iteration number
3931: - rnorm - relative norm of the residual

3933:   Level: developer

3935:   Note:
3936:   This routine is called by the `SNES` implementations.
3937:   It does not typically need to be called by the user.

3939: .seealso: [](ch_snes), `SNES`, `SNESMonitorSet()`
3940: @*/
3941: PetscErrorCode SNESMonitor(SNES snes, PetscInt iter, PetscReal rnorm)
3942: {
3943:   PetscInt i, n = snes->numbermonitors;

3945:   PetscFunctionBegin;
3946:   if (n > 0) SNESCheckFunctionNorm(snes, rnorm);
3947:   PetscCall(VecLockReadPush(snes->vec_sol));
3948:   for (i = 0; i < n; i++) PetscCall((*snes->monitor[i])(snes, iter, rnorm, snes->monitorcontext[i]));
3949:   PetscCall(VecLockReadPop(snes->vec_sol));
3950:   PetscFunctionReturn(PETSC_SUCCESS);
3951: }

3953: /* ------------ Routines to set performance monitoring options ----------- */

3955: /*MC
3956:     SNESMonitorFunction - functional form passed to `SNESMonitorSet()` to monitor convergence of nonlinear solver

3958:      Synopsis:
3959: #include <petscsnes.h>
3960:     PetscErrorCode SNESMonitorFunction(SNES snes, PetscInt its, PetscReal norm, void *mctx)

3962:      Collective

3964:     Input Parameters:
3965: +    snes - the `SNES` context
3966: .    its - iteration number
3967: .    norm - 2-norm function value (may be estimated)
3968: -    mctx - [optional] monitoring context

3970:    Level: advanced

3972: .seealso: [](ch_snes), `SNESMonitorSet()`, `SNESMonitorSet()`, `SNESMonitorGet()`
3973: M*/

3975: /*@C
3976:   SNESMonitorSet - Sets an ADDITIONAL function that is to be used at every
3977:   iteration of the nonlinear solver to display the iteration's
3978:   progress.

3980:   Logically Collective

3982:   Input Parameters:
3983: + snes           - the `SNES` context
3984: . f              - the monitor function,  for the calling sequence see `SNESMonitorFunction`
3985: . mctx           - [optional] user-defined context for private data for the
3986:           monitor routine (use `NULL` if no context is desired)
3987: - monitordestroy - [optional] routine that frees monitor context (may be `NULL`)

3989:   Options Database Keys:
3990: + -snes_monitor               - sets `SNESMonitorDefault()`
3991: . -snes_monitor draw::draw_lg - sets line graph monitor,
3992: - -snes_monitor_cancel        - cancels all monitors that have been hardwired into a code by calls to `SNESMonitorSet()`, but does not cancel those set via
3993:                             the options database.

3995:   Level: intermediate

3997:   Note:
3998:   Several different monitoring routines may be set by calling
3999:   `SNESMonitorSet()` multiple times; all will be called in the
4000:   order in which they were set.

4002:   Fortran Notes:
4003:   Only a single monitor function can be set for each `SNES` object

4005: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESMonitorDefault()`, `SNESMonitorCancel()`, `SNESMonitorFunction`
4006: @*/
4007: PetscErrorCode SNESMonitorSet(SNES snes, PetscErrorCode (*f)(SNES, PetscInt, PetscReal, void *), void *mctx, PetscErrorCode (*monitordestroy)(void **))
4008: {
4009:   PetscInt  i;
4010:   PetscBool identical;

4012:   PetscFunctionBegin;
4014:   for (i = 0; i < snes->numbermonitors; i++) {
4015:     PetscCall(PetscMonitorCompare((PetscErrorCode(*)(void))f, mctx, monitordestroy, (PetscErrorCode(*)(void))snes->monitor[i], snes->monitorcontext[i], snes->monitordestroy[i], &identical));
4016:     if (identical) PetscFunctionReturn(PETSC_SUCCESS);
4017:   }
4018:   PetscCheck(snes->numbermonitors < MAXSNESMONITORS, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Too many monitors set");
4019:   snes->monitor[snes->numbermonitors]          = f;
4020:   snes->monitordestroy[snes->numbermonitors]   = monitordestroy;
4021:   snes->monitorcontext[snes->numbermonitors++] = (void *)mctx;
4022:   PetscFunctionReturn(PETSC_SUCCESS);
4023: }

4025: /*@
4026:   SNESMonitorCancel - Clears all the monitor functions for a `SNES` object.

4028:   Logically Collective

4030:   Input Parameter:
4031: . snes - the `SNES` context

4033:   Options Database Key:
4034: . -snes_monitor_cancel - cancels all monitors that have been hardwired
4035:     into a code by calls to `SNESMonitorSet()`, but does not cancel those
4036:     set via the options database

4038:   Level: intermediate

4040:   Note:
4041:   There is no way to clear one specific monitor from a `SNES` object.

4043: .seealso: [](ch_snes), `SNES`, `SNESMonitorGet()`, `SNESMonitorDefault()`, `SNESMonitorSet()`
4044: @*/
4045: PetscErrorCode SNESMonitorCancel(SNES snes)
4046: {
4047:   PetscInt i;

4049:   PetscFunctionBegin;
4051:   for (i = 0; i < snes->numbermonitors; i++) {
4052:     if (snes->monitordestroy[i]) PetscCall((*snes->monitordestroy[i])(&snes->monitorcontext[i]));
4053:   }
4054:   snes->numbermonitors = 0;
4055:   PetscFunctionReturn(PETSC_SUCCESS);
4056: }

4058: /*MC
4059:     SNESConvergenceTestFunction - functional form used for testing of convergence of nonlinear solver

4061:      Synopsis:
4062: #include <petscsnes.h>
4063:      PetscErrorCode SNESConvergenceTest(SNES snes, PetscInt it, PetscReal xnorm, PetscReal gnorm, PetscReal f, SNESConvergedReason *reason, void *cctx)

4065:      Collective

4067:     Input Parameters:
4068: +    snes - the `SNES` context
4069: .    it - current iteration (0 is the first and is before any Newton step)
4070: .    xnorm - 2-norm of current iterate
4071: .    gnorm - 2-norm of current step
4072: .    f - 2-norm of function
4073: -    cctx - [optional] convergence context

4075:     Output Parameter:
4076: .    reason - reason for convergence/divergence, only needs to be set when convergence or divergence is detected

4078:    Level: intermediate

4080: .seealso: [](ch_snes), `SNES`, `SNESSolve`, `SNESSetConvergenceTest()`, `SNESGetConvergenceTest()`
4081: M*/

4083: /*@C
4084:   SNESSetConvergenceTest - Sets the function that is to be used
4085:   to test for convergence of the nonlinear iterative solution.

4087:   Logically Collective

4089:   Input Parameters:
4090: + snes                        - the `SNES` context
4091: . SNESConvergenceTestFunction - routine to test for convergence
4092: . cctx                        - [optional] context for private data for the convergence routine  (may be `NULL`)
4093: - destroy                     - [optional] destructor for the context (may be `NULL`; `PETSC_NULL_FUNCTION` in Fortran)

4095:   Level: advanced

4097: .seealso: [](ch_snes), `SNES`, `SNESConvergedDefault()`, `SNESConvergedSkip()`, `SNESConvergenceTestFunction`
4098: @*/
4099: PetscErrorCode SNESSetConvergenceTest(SNES snes, PetscErrorCode (*SNESConvergenceTestFunction)(SNES, PetscInt, PetscReal, PetscReal, PetscReal, SNESConvergedReason *, void *), void *cctx, PetscErrorCode (*destroy)(void *))
4100: {
4101:   PetscFunctionBegin;
4103:   if (!SNESConvergenceTestFunction) SNESConvergenceTestFunction = SNESConvergedSkip;
4104:   if (snes->ops->convergeddestroy) PetscCall((*snes->ops->convergeddestroy)(snes->cnvP));
4105:   snes->ops->converged        = SNESConvergenceTestFunction;
4106:   snes->ops->convergeddestroy = destroy;
4107:   snes->cnvP                  = cctx;
4108:   PetscFunctionReturn(PETSC_SUCCESS);
4109: }

4111: /*@
4112:   SNESGetConvergedReason - Gets the reason the `SNES` iteration was stopped.

4114:   Not Collective

4116:   Input Parameter:
4117: . snes - the `SNES` context

4119:   Output Parameter:
4120: . reason - negative value indicates diverged, positive value converged, see `SNESConvergedReason` for the individual convergence tests for complete lists

4122:   Options Database Key:
4123: . -snes_converged_reason - prints the reason to standard out

4125:   Level: intermediate

4127:   Note:
4128:   Should only be called after the call the `SNESSolve()` is complete, if it is called earlier it returns the value `SNES__CONVERGED_ITERATING`.

4130: .seealso: [](ch_snes), `SNESSolve()`, `SNESSetConvergenceTest()`, `SNESSetConvergedReason()`, `SNESConvergedReason`, `SNESGetConvergedReasonString()`
4131: @*/
4132: PetscErrorCode SNESGetConvergedReason(SNES snes, SNESConvergedReason *reason)
4133: {
4134:   PetscFunctionBegin;
4136:   PetscAssertPointer(reason, 2);
4137:   *reason = snes->reason;
4138:   PetscFunctionReturn(PETSC_SUCCESS);
4139: }

4141: /*@C
4142:   SNESGetConvergedReasonString - Return a human readable string for `SNESConvergedReason`

4144:   Not Collective

4146:   Input Parameter:
4147: . snes - the `SNES` context

4149:   Output Parameter:
4150: . strreason - a human readable string that describes `SNES` converged reason

4152:   Level: beginner

4154: .seealso: [](ch_snes), `SNES`, `SNESGetConvergedReason()`
4155: @*/
4156: PetscErrorCode SNESGetConvergedReasonString(SNES snes, const char **strreason)
4157: {
4158:   PetscFunctionBegin;
4160:   PetscAssertPointer(strreason, 2);
4161:   *strreason = SNESConvergedReasons[snes->reason];
4162:   PetscFunctionReturn(PETSC_SUCCESS);
4163: }

4165: /*@
4166:   SNESSetConvergedReason - Sets the reason the `SNES` iteration was stopped.

4168:   Not Collective

4170:   Input Parameters:
4171: + snes   - the `SNES` context
4172: - reason - negative value indicates diverged, positive value converged, see `SNESConvergedReason` or the
4173:             manual pages for the individual convergence tests for complete lists

4175:   Level: developer

4177:   Developer Notes:
4178:   Called inside the various `SNESSolve()` implementations

4180: .seealso: [](ch_snes), `SNESGetConvergedReason()`, `SNESSetConvergenceTest()`, `SNESConvergedReason`
4181: @*/
4182: PetscErrorCode SNESSetConvergedReason(SNES snes, SNESConvergedReason reason)
4183: {
4184:   PetscFunctionBegin;
4186:   PetscCheck(!snes->errorifnotconverged || reason > 0, PetscObjectComm((PetscObject)snes), PETSC_ERR_PLIB, "SNES code should have previously errored due to negative reason");
4187:   snes->reason = reason;
4188:   PetscFunctionReturn(PETSC_SUCCESS);
4189: }

4191: /*@
4192:   SNESSetConvergenceHistory - Sets the array used to hold the convergence history.

4194:   Logically Collective

4196:   Input Parameters:
4197: + snes  - iterative context obtained from `SNESCreate()`
4198: . a     - array to hold history, this array will contain the function norms computed at each step
4199: . its   - integer array holds the number of linear iterations for each solve.
4200: . na    - size of a and its
4201: - reset - `PETSC_TRUE` indicates each new nonlinear solve resets the history counter to zero,
4202:            else it continues storing new values for new nonlinear solves after the old ones

4204:   Level: intermediate

4206:   Notes:
4207:   If 'a' and 'its' are `NULL` then space is allocated for the history. If 'na' `PETSC_DECIDE` or `PETSC_DEFAULT` then a
4208:   default array of length 10000 is allocated.

4210:   This routine is useful, e.g., when running a code for purposes
4211:   of accurate performance monitoring, when no I/O should be done
4212:   during the section of code that is being timed.

4214: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetConvergenceHistory()`
4215: @*/
4216: PetscErrorCode SNESSetConvergenceHistory(SNES snes, PetscReal a[], PetscInt its[], PetscInt na, PetscBool reset)
4217: {
4218:   PetscFunctionBegin;
4220:   if (a) PetscAssertPointer(a, 2);
4221:   if (its) PetscAssertPointer(its, 3);
4222:   if (!a) {
4223:     if (na == PETSC_DECIDE || na == PETSC_DEFAULT) na = 1000;
4224:     PetscCall(PetscCalloc2(na, &a, na, &its));
4225:     snes->conv_hist_alloc = PETSC_TRUE;
4226:   }
4227:   snes->conv_hist       = a;
4228:   snes->conv_hist_its   = its;
4229:   snes->conv_hist_max   = (size_t)na;
4230:   snes->conv_hist_len   = 0;
4231:   snes->conv_hist_reset = reset;
4232:   PetscFunctionReturn(PETSC_SUCCESS);
4233: }

4235: #if defined(PETSC_HAVE_MATLAB)
4236:   #include <engine.h> /* MATLAB include file */
4237:   #include <mex.h>    /* MATLAB include file */

4239: PETSC_EXTERN mxArray *SNESGetConvergenceHistoryMatlab(SNES snes)
4240: {
4241:   mxArray   *mat;
4242:   PetscInt   i;
4243:   PetscReal *ar;

4245:   mat = mxCreateDoubleMatrix(snes->conv_hist_len, 1, mxREAL);
4246:   ar  = (PetscReal *)mxGetData(mat);
4247:   for (i = 0; i < snes->conv_hist_len; i++) ar[i] = snes->conv_hist[i];
4248:   return mat;
4249: }
4250: #endif

4252: /*@C
4253:   SNESGetConvergenceHistory - Gets the array used to hold the convergence history.

4255:   Not Collective

4257:   Input Parameter:
4258: . snes - iterative context obtained from `SNESCreate()`

4260:   Output Parameters:
4261: + a   - array to hold history, usually was set with `SNESSetConvergenceHistory()`
4262: . its - integer array holds the number of linear iterations (or
4263:          negative if not converged) for each solve.
4264: - na  - size of `a` and `its`

4266:   Level: intermediate

4268:   Note:
4269:   This routine is useful, e.g., when running a code for purposes
4270:   of accurate performance monitoring, when no I/O should be done
4271:   during the section of code that is being timed.

4273:   Fortran Notes:
4274:   The calling sequence for this routine in Fortran is
4275: .vb
4276:     call SNESGetConvergenceHistory(SNES snes, integer na, integer ierr)
4277: .ve

4279: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetConvergenceHistory()`
4280: @*/
4281: PetscErrorCode SNESGetConvergenceHistory(SNES snes, PetscReal *a[], PetscInt *its[], PetscInt *na)
4282: {
4283:   PetscFunctionBegin;
4285:   if (a) *a = snes->conv_hist;
4286:   if (its) *its = snes->conv_hist_its;
4287:   if (na) *na = (PetscInt)snes->conv_hist_len;
4288:   PetscFunctionReturn(PETSC_SUCCESS);
4289: }

4291: /*@C
4292:   SNESSetUpdate - Sets the general-purpose update function called
4293:   at the beginning of every iteration of the nonlinear solve. Specifically
4294:   it is called just before the Jacobian is "evaluated".

4296:   Logically Collective

4298:   Input Parameters:
4299: + snes - The nonlinear solver context
4300: - func - The function

4302:   Calling sequence of `func`:
4303: $ PetscErrorCode func(SNES snes, PetscInt step);
4304: + snes - the nonlinear solver context
4305: - step - The current step of the iteration

4307:   Level: advanced

4309:   Note:
4310:   This is NOT what one uses to update the ghost points before a function evaluation, that should be done at the beginning of your function provided
4311:   to `SNESSetFunction()`, or `SNESSetPicard()`
4312:   This is not used by most users.

4314:   There are a variety of function hooks one many set that are called at different stages of the nonlinear solution process, see the functions listed below.

4316: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetJacobian()`, `SNESLineSearchSetPreCheck()`, `SNESLineSearchSetPostCheck()`, `SNESNewtonTRSetPreCheck()`, `SNESNewtonTRSetPostCheck()`,
4317:          `SNESMonitorSet()`, `SNESSetDivergenceTest()`
4318: @*/
4319: PetscErrorCode SNESSetUpdate(SNES snes, PetscErrorCode (*func)(SNES snes, PetscInt step))
4320: {
4321:   PetscFunctionBegin;
4323:   snes->ops->update = func;
4324:   PetscFunctionReturn(PETSC_SUCCESS);
4325: }

4327: /*@C
4328:   SNESConvergedReasonView - Displays the reason a `SNES` solve converged or diverged to a viewer

4330:   Collective

4332:   Input Parameters:
4333: + snes   - iterative context obtained from `SNESCreate()`
4334: - viewer - the viewer to display the reason

4336:   Options Database Keys:
4337: + -snes_converged_reason          - print reason for converged or diverged, also prints number of iterations
4338: - -snes_converged_reason ::failed - only print reason and number of iterations when diverged

4340:   Note:
4341:   To change the format of the output call `PetscViewerPushFormat`(viewer,format) before this call. Use `PETSC_VIEWER_DEFAULT` for the default,
4342:   use `PETSC_VIEWER_FAILED` to only display a reason if it fails.

4344:   Level: beginner

4346: .seealso: [](ch_snes), `SNESConvergedReason`, `PetscViewer`, `SNES`,
4347:           `SNESCreate()`, `SNESSetUp()`, `SNESDestroy()`, `SNESSetTolerances()`, `SNESConvergedDefault()`, `SNESGetConvergedReason()`,
4348:           `SNESConvergedReasonViewFromOptions()`,
4349:           `PetscViewerPushFormat()`, `PetscViewerPopFormat()`
4350: @*/
4351: PetscErrorCode SNESConvergedReasonView(SNES snes, PetscViewer viewer)
4352: {
4353:   PetscViewerFormat format;
4354:   PetscBool         isAscii;

4356:   PetscFunctionBegin;
4357:   if (!viewer) viewer = PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes));
4358:   PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isAscii));
4359:   if (isAscii) {
4360:     PetscCall(PetscViewerGetFormat(viewer, &format));
4361:     PetscCall(PetscViewerASCIIAddTab(viewer, ((PetscObject)snes)->tablevel));
4362:     if (format == PETSC_VIEWER_ASCII_INFO_DETAIL) {
4363:       DM       dm;
4364:       Vec      u;
4365:       PetscDS  prob;
4366:       PetscInt Nf, f;
4367:       PetscErrorCode (**exactSol)(PetscInt, PetscReal, const PetscReal[], PetscInt, PetscScalar[], void *);
4368:       void    **exactCtx;
4369:       PetscReal error;

4371:       PetscCall(SNESGetDM(snes, &dm));
4372:       PetscCall(SNESGetSolution(snes, &u));
4373:       PetscCall(DMGetDS(dm, &prob));
4374:       PetscCall(PetscDSGetNumFields(prob, &Nf));
4375:       PetscCall(PetscMalloc2(Nf, &exactSol, Nf, &exactCtx));
4376:       for (f = 0; f < Nf; ++f) PetscCall(PetscDSGetExactSolution(prob, f, &exactSol[f], &exactCtx[f]));
4377:       PetscCall(DMComputeL2Diff(dm, 0.0, exactSol, exactCtx, u, &error));
4378:       PetscCall(PetscFree2(exactSol, exactCtx));
4379:       if (error < 1.0e-11) PetscCall(PetscViewerASCIIPrintf(viewer, "L_2 Error: < 1.0e-11\n"));
4380:       else PetscCall(PetscViewerASCIIPrintf(viewer, "L_2 Error: %g\n", (double)error));
4381:     }
4382:     if (snes->reason > 0 && format != PETSC_VIEWER_FAILED) {
4383:       if (((PetscObject)snes)->prefix) {
4384:         PetscCall(PetscViewerASCIIPrintf(viewer, "Nonlinear %s solve converged due to %s iterations %" PetscInt_FMT "\n", ((PetscObject)snes)->prefix, SNESConvergedReasons[snes->reason], snes->iter));
4385:       } else {
4386:         PetscCall(PetscViewerASCIIPrintf(viewer, "Nonlinear solve converged due to %s iterations %" PetscInt_FMT "\n", SNESConvergedReasons[snes->reason], snes->iter));
4387:       }
4388:     } else if (snes->reason <= 0) {
4389:       if (((PetscObject)snes)->prefix) {
4390:         PetscCall(PetscViewerASCIIPrintf(viewer, "Nonlinear %s solve did not converge due to %s iterations %" PetscInt_FMT "\n", ((PetscObject)snes)->prefix, SNESConvergedReasons[snes->reason], snes->iter));
4391:       } else {
4392:         PetscCall(PetscViewerASCIIPrintf(viewer, "Nonlinear solve did not converge due to %s iterations %" PetscInt_FMT "\n", SNESConvergedReasons[snes->reason], snes->iter));
4393:       }
4394:     }
4395:     PetscCall(PetscViewerASCIISubtractTab(viewer, ((PetscObject)snes)->tablevel));
4396:   }
4397:   PetscFunctionReturn(PETSC_SUCCESS);
4398: }

4400: /*@C
4401:   SNESConvergedReasonViewSet - Sets an ADDITIONAL function that is to be used at the
4402:   end of the nonlinear solver to display the convergence reason of the nonlinear solver.

4404:   Logically Collective

4406:   Input Parameters:
4407: + snes              - the `SNES` context
4408: . f                 - the snes converged reason view function
4409: . vctx              - [optional] user-defined context for private data for the
4410:           snes converged reason view routine (use `NULL` if no context is desired)
4411: - reasonviewdestroy - [optional] routine that frees reasonview context (may be `NULL`)

4413:   Options Database Keys:
4414: + -snes_converged_reason             - sets a default `SNESConvergedReasonView()`
4415: - -snes_converged_reason_view_cancel - cancels all converged reason viewers that have
4416:                             been hardwired into a code by
4417:                             calls to `SNESConvergedReasonViewSet()`, but
4418:                             does not cancel those set via
4419:                             the options database.

4421:   Level: intermediate

4423:   Note:
4424:   Several different converged reason view routines may be set by calling
4425:   `SNESConvergedReasonViewSet()` multiple times; all will be called in the
4426:   order in which they were set.

4428: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESConvergedReason`, `SNESGetConvergedReason()`, `SNESConvergedReasonView()`, `SNESConvergedReasonViewCancel()`
4429: @*/
4430: PetscErrorCode SNESConvergedReasonViewSet(SNES snes, PetscErrorCode (*f)(SNES, void *), void *vctx, PetscErrorCode (*reasonviewdestroy)(void **))
4431: {
4432:   PetscInt  i;
4433:   PetscBool identical;

4435:   PetscFunctionBegin;
4437:   for (i = 0; i < snes->numberreasonviews; i++) {
4438:     PetscCall(PetscMonitorCompare((PetscErrorCode(*)(void))f, vctx, reasonviewdestroy, (PetscErrorCode(*)(void))snes->reasonview[i], snes->reasonviewcontext[i], snes->reasonviewdestroy[i], &identical));
4439:     if (identical) PetscFunctionReturn(PETSC_SUCCESS);
4440:   }
4441:   PetscCheck(snes->numberreasonviews < MAXSNESREASONVIEWS, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Too many SNES reasonview set");
4442:   snes->reasonview[snes->numberreasonviews]          = f;
4443:   snes->reasonviewdestroy[snes->numberreasonviews]   = reasonviewdestroy;
4444:   snes->reasonviewcontext[snes->numberreasonviews++] = (void *)vctx;
4445:   PetscFunctionReturn(PETSC_SUCCESS);
4446: }

4448: /*@
4449:   SNESConvergedReasonViewFromOptions - Processes command line options to determine if/how a `SNESConvergedReason` is to be viewed.
4450:   All the user-provided convergedReasonView routines will be involved as well, if they exist.

4452:   Collective

4454:   Input Parameter:
4455: . snes - the `SNES` object

4457:   Level: advanced

4459: .seealso: [](ch_snes), `SNES`, `SNESConvergedReason`, `SNESConvergedReasonViewSet()`, `SNESCreate()`, `SNESSetUp()`, `SNESDestroy()`,
4460:           `SNESSetTolerances()`, `SNESConvergedDefault()`, `SNESGetConvergedReason()`, `SNESConvergedReasonView()`
4461: @*/
4462: PetscErrorCode SNESConvergedReasonViewFromOptions(SNES snes)
4463: {
4464:   PetscViewer       viewer;
4465:   PetscBool         flg;
4466:   static PetscBool  incall = PETSC_FALSE;
4467:   PetscViewerFormat format;
4468:   PetscInt          i;

4470:   PetscFunctionBegin;
4471:   if (incall) PetscFunctionReturn(PETSC_SUCCESS);
4472:   incall = PETSC_TRUE;

4474:   /* All user-provided viewers are called first, if they exist. */
4475:   for (i = 0; i < snes->numberreasonviews; i++) PetscCall((*snes->reasonview[i])(snes, snes->reasonviewcontext[i]));

4477:   /* Call PETSc default routine if users ask for it */
4478:   PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_converged_reason", &viewer, &format, &flg));
4479:   if (flg) {
4480:     PetscCall(PetscViewerPushFormat(viewer, format));
4481:     PetscCall(SNESConvergedReasonView(snes, viewer));
4482:     PetscCall(PetscViewerPopFormat(viewer));
4483:     PetscCall(PetscViewerDestroy(&viewer));
4484:   }
4485:   incall = PETSC_FALSE;
4486:   PetscFunctionReturn(PETSC_SUCCESS);
4487: }

4489: /*@
4490:   SNESSolve - Solves a nonlinear system F(x) = b.
4491:   Call `SNESSolve()` after calling `SNESCreate()` and optional routines of the form `SNESSetXXX()`.

4493:   Collective

4495:   Input Parameters:
4496: + snes - the `SNES` context
4497: . b    - the constant part of the equation F(x) = b, or `NULL` to use zero.
4498: - x    - the solution vector.

4500:   Level: beginner

4502:   Note:
4503:   The user should initialize the vector,x, with the initial guess
4504:   for the nonlinear solve prior to calling `SNESSolve()`.  In particular,
4505:   to employ an initial guess of zero, the user should explicitly set
4506:   this vector to zero by calling `VecSet()`.

4508: .seealso: [](ch_snes), `SNES`, `SNESCreate()`, `SNESDestroy()`, `SNESSetFunction()`, `SNESSetJacobian()`, `SNESSetGridSequence()`, `SNESGetSolution()`,
4509:           `SNESNewtonTRSetPreCheck()`, `SNESNewtonTRGetPreCheck()`, `SNESNewtonTRSetPostCheck()`, `SNESNewtonTRGetPostCheck()`,
4510:           `SNESLineSearchSetPostCheck()`, `SNESLineSearchGetPostCheck()`, `SNESLineSearchSetPreCheck()`, `SNESLineSearchGetPreCheck()`
4511: @*/
4512: PetscErrorCode SNESSolve(SNES snes, Vec b, Vec x)
4513: {
4514:   PetscBool flg;
4515:   PetscInt  grid;
4516:   Vec       xcreated = NULL;
4517:   DM        dm;

4519:   PetscFunctionBegin;
4522:   if (x) PetscCheckSameComm(snes, 1, x, 3);
4524:   if (b) PetscCheckSameComm(snes, 1, b, 2);

4526:   /* High level operations using the nonlinear solver */
4527:   {
4528:     PetscViewer       viewer;
4529:     PetscViewerFormat format;
4530:     PetscInt          num;
4531:     PetscBool         flg;
4532:     static PetscBool  incall = PETSC_FALSE;

4534:     if (!incall) {
4535:       /* Estimate the convergence rate of the discretization */
4536:       PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_convergence_estimate", &viewer, &format, &flg));
4537:       if (flg) {
4538:         PetscConvEst conv;
4539:         DM           dm;
4540:         PetscReal   *alpha; /* Convergence rate of the solution error for each field in the L_2 norm */
4541:         PetscInt     Nf;

4543:         incall = PETSC_TRUE;
4544:         PetscCall(SNESGetDM(snes, &dm));
4545:         PetscCall(DMGetNumFields(dm, &Nf));
4546:         PetscCall(PetscCalloc1(Nf, &alpha));
4547:         PetscCall(PetscConvEstCreate(PetscObjectComm((PetscObject)snes), &conv));
4548:         PetscCall(PetscConvEstSetSolver(conv, (PetscObject)snes));
4549:         PetscCall(PetscConvEstSetFromOptions(conv));
4550:         PetscCall(PetscConvEstSetUp(conv));
4551:         PetscCall(PetscConvEstGetConvRate(conv, alpha));
4552:         PetscCall(PetscViewerPushFormat(viewer, format));
4553:         PetscCall(PetscConvEstRateView(conv, alpha, viewer));
4554:         PetscCall(PetscViewerPopFormat(viewer));
4555:         PetscCall(PetscViewerDestroy(&viewer));
4556:         PetscCall(PetscConvEstDestroy(&conv));
4557:         PetscCall(PetscFree(alpha));
4558:         incall = PETSC_FALSE;
4559:       }
4560:       /* Adaptively refine the initial grid */
4561:       num = 1;
4562:       PetscCall(PetscOptionsGetInt(NULL, ((PetscObject)snes)->prefix, "-snes_adapt_initial", &num, &flg));
4563:       if (flg) {
4564:         DMAdaptor adaptor;

4566:         incall = PETSC_TRUE;
4567:         PetscCall(DMAdaptorCreate(PetscObjectComm((PetscObject)snes), &adaptor));
4568:         PetscCall(DMAdaptorSetSolver(adaptor, snes));
4569:         PetscCall(DMAdaptorSetSequenceLength(adaptor, num));
4570:         PetscCall(DMAdaptorSetFromOptions(adaptor));
4571:         PetscCall(DMAdaptorSetUp(adaptor));
4572:         PetscCall(DMAdaptorAdapt(adaptor, x, DM_ADAPTATION_INITIAL, &dm, &x));
4573:         PetscCall(DMAdaptorDestroy(&adaptor));
4574:         incall = PETSC_FALSE;
4575:       }
4576:       /* Use grid sequencing to adapt */
4577:       num = 0;
4578:       PetscCall(PetscOptionsGetInt(NULL, ((PetscObject)snes)->prefix, "-snes_adapt_sequence", &num, NULL));
4579:       if (num) {
4580:         DMAdaptor adaptor;

4582:         incall = PETSC_TRUE;
4583:         PetscCall(DMAdaptorCreate(PetscObjectComm((PetscObject)snes), &adaptor));
4584:         PetscCall(DMAdaptorSetSolver(adaptor, snes));
4585:         PetscCall(DMAdaptorSetSequenceLength(adaptor, num));
4586:         PetscCall(DMAdaptorSetFromOptions(adaptor));
4587:         PetscCall(DMAdaptorSetUp(adaptor));
4588:         PetscCall(DMAdaptorAdapt(adaptor, x, DM_ADAPTATION_SEQUENTIAL, &dm, &x));
4589:         PetscCall(DMAdaptorDestroy(&adaptor));
4590:         incall = PETSC_FALSE;
4591:       }
4592:     }
4593:   }
4594:   if (!x) x = snes->vec_sol;
4595:   if (!x) {
4596:     PetscCall(SNESGetDM(snes, &dm));
4597:     PetscCall(DMCreateGlobalVector(dm, &xcreated));
4598:     x = xcreated;
4599:   }
4600:   PetscCall(SNESViewFromOptions(snes, NULL, "-snes_view_pre"));

4602:   for (grid = 0; grid < snes->gridsequence; grid++) PetscCall(PetscViewerASCIIPushTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes))));
4603:   for (grid = 0; grid < snes->gridsequence + 1; grid++) {
4604:     /* set solution vector */
4605:     if (!grid) PetscCall(PetscObjectReference((PetscObject)x));
4606:     PetscCall(VecDestroy(&snes->vec_sol));
4607:     snes->vec_sol = x;
4608:     PetscCall(SNESGetDM(snes, &dm));

4610:     /* set affine vector if provided */
4611:     if (b) PetscCall(PetscObjectReference((PetscObject)b));
4612:     PetscCall(VecDestroy(&snes->vec_rhs));
4613:     snes->vec_rhs = b;

4615:     if (snes->vec_rhs) PetscCheck(snes->vec_func != snes->vec_rhs, PETSC_COMM_SELF, PETSC_ERR_ARG_IDN, "Right hand side vector cannot be function vector");
4616:     PetscCheck(snes->vec_func != snes->vec_sol, PETSC_COMM_SELF, PETSC_ERR_ARG_IDN, "Solution vector cannot be function vector");
4617:     PetscCheck(snes->vec_rhs != snes->vec_sol, PETSC_COMM_SELF, PETSC_ERR_ARG_IDN, "Solution vector cannot be right hand side vector");
4618:     if (!snes->vec_sol_update /* && snes->vec_sol */) PetscCall(VecDuplicate(snes->vec_sol, &snes->vec_sol_update));
4619:     PetscCall(DMShellSetGlobalVector(dm, snes->vec_sol));
4620:     PetscCall(SNESSetUp(snes));

4622:     if (!grid) {
4623:       if (snes->ops->computeinitialguess) PetscCallBack("SNES callback initial guess", (*snes->ops->computeinitialguess)(snes, snes->vec_sol, snes->initialguessP));
4624:     }

4626:     if (snes->conv_hist_reset) snes->conv_hist_len = 0;
4627:     if (snes->counters_reset) {
4628:       snes->nfuncs      = 0;
4629:       snes->linear_its  = 0;
4630:       snes->numFailures = 0;
4631:     }

4633:     snes->reason = SNES_CONVERGED_ITERATING;
4634:     PetscCall(PetscLogEventBegin(SNES_Solve, snes, 0, 0, 0));
4635:     PetscUseTypeMethod(snes, solve);
4636:     PetscCall(PetscLogEventEnd(SNES_Solve, snes, 0, 0, 0));
4637:     PetscCheck(snes->reason, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Internal error, solver %s returned without setting converged reason", ((PetscObject)snes)->type_name);
4638:     snes->domainerror = PETSC_FALSE; /* clear the flag if it has been set */

4640:     if (snes->lagjac_persist) snes->jac_iter += snes->iter;
4641:     if (snes->lagpre_persist) snes->pre_iter += snes->iter;

4643:     PetscCall(PetscOptionsGetViewer(PetscObjectComm((PetscObject)snes), ((PetscObject)snes)->options, ((PetscObject)snes)->prefix, "-snes_test_local_min", NULL, NULL, &flg));
4644:     if (flg && !PetscPreLoadingOn) PetscCall(SNESTestLocalMin(snes));
4645:     /* Call converged reason views. This may involve user-provided viewers as well */
4646:     PetscCall(SNESConvergedReasonViewFromOptions(snes));

4648:     if (snes->errorifnotconverged) PetscCheck(snes->reason >= 0, PetscObjectComm((PetscObject)snes), PETSC_ERR_NOT_CONVERGED, "SNESSolve has not converged");
4649:     if (snes->reason < 0) break;
4650:     if (grid < snes->gridsequence) {
4651:       DM  fine;
4652:       Vec xnew;
4653:       Mat interp;

4655:       PetscCall(DMRefine(snes->dm, PetscObjectComm((PetscObject)snes), &fine));
4656:       PetscCheck(fine, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_INCOMP, "DMRefine() did not perform any refinement, cannot continue grid sequencing");
4657:       PetscCall(DMCreateInterpolation(snes->dm, fine, &interp, NULL));
4658:       PetscCall(DMCreateGlobalVector(fine, &xnew));
4659:       PetscCall(MatInterpolate(interp, x, xnew));
4660:       PetscCall(DMInterpolate(snes->dm, interp, fine));
4661:       PetscCall(MatDestroy(&interp));
4662:       x = xnew;

4664:       PetscCall(SNESReset(snes));
4665:       PetscCall(SNESSetDM(snes, fine));
4666:       PetscCall(SNESResetFromOptions(snes));
4667:       PetscCall(DMDestroy(&fine));
4668:       PetscCall(PetscViewerASCIIPopTab(PETSC_VIEWER_STDOUT_(PetscObjectComm((PetscObject)snes))));
4669:     }
4670:   }
4671:   PetscCall(SNESViewFromOptions(snes, NULL, "-snes_view"));
4672:   PetscCall(VecViewFromOptions(snes->vec_sol, (PetscObject)snes, "-snes_view_solution"));
4673:   PetscCall(DMMonitor(snes->dm));
4674:   PetscCall(SNESMonitorPauseFinal_Internal(snes));

4676:   PetscCall(VecDestroy(&xcreated));
4677:   PetscCall(PetscObjectSAWsBlock((PetscObject)snes));
4678:   PetscFunctionReturn(PETSC_SUCCESS);
4679: }

4681: /* --------- Internal routines for SNES Package --------- */

4683: /*@C
4684:   SNESSetType - Sets the method for the nonlinear solver.

4686:   Collective

4688:   Input Parameters:
4689: + snes - the `SNES` context
4690: - type - a known method

4692:   Options Database Key:
4693: . -snes_type <type> - Sets the method; use -help for a list
4694:    of available methods (for instance, newtonls or newtontr)

4696:   Level: intermediate

4698:   Notes:
4699:   See "petsc/include/petscsnes.h" for available methods (for instance)
4700: +    `SNESNEWTONLS` - Newton's method with line search
4701:   (systems of nonlinear equations)
4702: -    `SNESNEWTONTR` - Newton's method with trust region
4703:   (systems of nonlinear equations)

4705:   Normally, it is best to use the `SNESSetFromOptions()` command and then
4706:   set the `SNES` solver type from the options database rather than by using
4707:   this routine.  Using the options database provides the user with
4708:   maximum flexibility in evaluating the many nonlinear solvers.
4709:   The `SNESSetType()` routine is provided for those situations where it
4710:   is necessary to set the nonlinear solver independently of the command
4711:   line or options database.  This might be the case, for example, when
4712:   the choice of solver changes during the execution of the program,
4713:   and the user's application is taking responsibility for choosing the
4714:   appropriate method.

4716:   Developer Notes:
4717:   `SNESRegister()` adds a constructor for a new `SNESType` to `SNESList`, `SNESSetType()` locates
4718:   the constructor in that list and calls it to create the specific object.

4720: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESType`, `SNESCreate()`, `SNESDestroy()`, `SNESGetType()`, `SNESSetFromOptions()`
4721: @*/
4722: PetscErrorCode SNESSetType(SNES snes, SNESType type)
4723: {
4724:   PetscBool match;
4725:   PetscErrorCode (*r)(SNES);

4727:   PetscFunctionBegin;
4729:   PetscAssertPointer(type, 2);

4731:   PetscCall(PetscObjectTypeCompare((PetscObject)snes, type, &match));
4732:   if (match) PetscFunctionReturn(PETSC_SUCCESS);

4734:   PetscCall(PetscFunctionListFind(SNESList, type, &r));
4735:   PetscCheck(r, PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_UNKNOWN_TYPE, "Unable to find requested SNES type %s", type);
4736:   /* Destroy the previous private SNES context */
4737:   PetscTryTypeMethod(snes, destroy);
4738:   /* Reinitialize function pointers in SNESOps structure */
4739:   snes->ops->setup          = NULL;
4740:   snes->ops->solve          = NULL;
4741:   snes->ops->view           = NULL;
4742:   snes->ops->setfromoptions = NULL;
4743:   snes->ops->destroy        = NULL;

4745:   /* It may happen the user has customized the line search before calling SNESSetType */
4746:   if (((PetscObject)snes)->type_name) PetscCall(SNESLineSearchDestroy(&snes->linesearch));

4748:   /* Call the SNESCreate_XXX routine for this particular Nonlinear solver */
4749:   snes->setupcalled = PETSC_FALSE;

4751:   PetscCall(PetscObjectChangeTypeName((PetscObject)snes, type));
4752:   PetscCall((*r)(snes));
4753:   PetscFunctionReturn(PETSC_SUCCESS);
4754: }

4756: /*@C
4757:   SNESGetType - Gets the `SNES` method type and name (as a string).

4759:   Not Collective

4761:   Input Parameter:
4762: . snes - nonlinear solver context

4764:   Output Parameter:
4765: . type - `SNES` method (a character string)

4767:   Level: intermediate

4769: .seealso: [](ch_snes), `SNESSetType()`, `SNESType`, `SNESSetFromOptions()`, `SNES`
4770: @*/
4771: PetscErrorCode SNESGetType(SNES snes, SNESType *type)
4772: {
4773:   PetscFunctionBegin;
4775:   PetscAssertPointer(type, 2);
4776:   *type = ((PetscObject)snes)->type_name;
4777:   PetscFunctionReturn(PETSC_SUCCESS);
4778: }

4780: /*@
4781:   SNESSetSolution - Sets the solution vector for use by the `SNES` routines.

4783:   Logically Collective

4785:   Input Parameters:
4786: + snes - the `SNES` context obtained from `SNESCreate()`
4787: - u    - the solution vector

4789:   Level: beginner

4791: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESGetSolution()`, `Vec`
4792: @*/
4793: PetscErrorCode SNESSetSolution(SNES snes, Vec u)
4794: {
4795:   DM dm;

4797:   PetscFunctionBegin;
4800:   PetscCall(PetscObjectReference((PetscObject)u));
4801:   PetscCall(VecDestroy(&snes->vec_sol));

4803:   snes->vec_sol = u;

4805:   PetscCall(SNESGetDM(snes, &dm));
4806:   PetscCall(DMShellSetGlobalVector(dm, u));
4807:   PetscFunctionReturn(PETSC_SUCCESS);
4808: }

4810: /*@
4811:   SNESGetSolution - Returns the vector where the approximate solution is
4812:   stored. This is the fine grid solution when using `SNESSetGridSequence()`.

4814:   Not Collective, but x is parallel if snes is parallel

4816:   Input Parameter:
4817: . snes - the `SNES` context

4819:   Output Parameter:
4820: . x - the solution

4822:   Level: intermediate

4824: .seealso: [](ch_snes), `SNESSetSolution()`, `SNESSolve()`, `SNES`, `SNESGetSolutionUpdate()`, `SNESGetFunction()`
4825: @*/
4826: PetscErrorCode SNESGetSolution(SNES snes, Vec *x)
4827: {
4828:   PetscFunctionBegin;
4830:   PetscAssertPointer(x, 2);
4831:   *x = snes->vec_sol;
4832:   PetscFunctionReturn(PETSC_SUCCESS);
4833: }

4835: /*@
4836:   SNESGetSolutionUpdate - Returns the vector where the solution update is
4837:   stored.

4839:   Not Collective, but x is parallel if snes is parallel

4841:   Input Parameter:
4842: . snes - the `SNES` context

4844:   Output Parameter:
4845: . x - the solution update

4847:   Level: advanced

4849: .seealso: [](ch_snes), `SNES`, `SNESGetSolution()`, `SNESGetFunction()`
4850: @*/
4851: PetscErrorCode SNESGetSolutionUpdate(SNES snes, Vec *x)
4852: {
4853:   PetscFunctionBegin;
4855:   PetscAssertPointer(x, 2);
4856:   *x = snes->vec_sol_update;
4857:   PetscFunctionReturn(PETSC_SUCCESS);
4858: }

4860: /*@C
4861:   SNESGetFunction - Returns the function that defines the nonlinear system set with `SNESSetFunction()`

4863:   Not Collective, but r is parallel if snes is parallel. Collective if r is requested, but has not been created yet.

4865:   Input Parameter:
4866: . snes - the `SNES` context

4868:   Output Parameters:
4869: + r   - the vector that is used to store residuals (or `NULL` if you don't want it)
4870: . f   - the function (or `NULL` if you don't want it);  for calling sequence see `SNESFunction`
4871: - ctx - the function context (or `NULL` if you don't want it)

4873:   Level: advanced

4875:   Note:
4876:   The vector `r` DOES NOT, in general, contain the current value of the `SNES` nonlinear function

4878: .seealso: [](ch_snes), `SNES`, `SNESSolve()`, `SNESSetFunction()`, `SNESGetSolution()`, `SNESFunction`
4879: @*/
4880: PetscErrorCode SNESGetFunction(SNES snes, Vec *r, PetscErrorCode (**f)(SNES, Vec, Vec, void *), void **ctx)
4881: {
4882:   DM dm;

4884:   PetscFunctionBegin;
4886:   if (r) {
4887:     if (!snes->vec_func) {
4888:       if (snes->vec_rhs) {
4889:         PetscCall(VecDuplicate(snes->vec_rhs, &snes->vec_func));
4890:       } else if (snes->vec_sol) {
4891:         PetscCall(VecDuplicate(snes->vec_sol, &snes->vec_func));
4892:       } else if (snes->dm) {
4893:         PetscCall(DMCreateGlobalVector(snes->dm, &snes->vec_func));
4894:       }
4895:     }
4896:     *r = snes->vec_func;
4897:   }
4898:   PetscCall(SNESGetDM(snes, &dm));
4899:   PetscCall(DMSNESGetFunction(dm, f, ctx));
4900:   PetscFunctionReturn(PETSC_SUCCESS);
4901: }

4903: /*@C
4904:   SNESGetNGS - Returns the function and context set with `SNESSetNGS()`

4906:   Input Parameter:
4907: . snes - the `SNES` context

4909:   Output Parameters:
4910: + f   - the function (or `NULL`) see `SNESSetNGS()` for details
4911: - ctx - the function context (or `NULL`)

4913:   Level: advanced

4915: .seealso: [](ch_snes), `SNESSetNGS()`, `SNESGetFunction()`
4916: @*/
4917: PetscErrorCode SNESGetNGS(SNES snes, PetscErrorCode (**f)(SNES, Vec, Vec, void *), void **ctx)
4918: {
4919:   DM dm;

4921:   PetscFunctionBegin;
4923:   PetscCall(SNESGetDM(snes, &dm));
4924:   PetscCall(DMSNESGetNGS(dm, f, ctx));
4925:   PetscFunctionReturn(PETSC_SUCCESS);
4926: }

4928: /*@C
4929:   SNESSetOptionsPrefix - Sets the prefix used for searching for all
4930:   `SNES` options in the database.

4932:   Logically Collective

4934:   Input Parameters:
4935: + snes   - the `SNES` context
4936: - prefix - the prefix to prepend to all option names

4938:   Level: advanced

4940:   Note:
4941:   A hyphen (-) must NOT be given at the beginning of the prefix name.
4942:   The first character of all runtime options is AUTOMATICALLY the hyphen.

4944: .seealso: [](ch_snes), `SNES`, `SNESSetFromOptions()`, `SNESAppendOptionsPrefix()`
4945: @*/
4946: PetscErrorCode SNESSetOptionsPrefix(SNES snes, const char prefix[])
4947: {
4948:   PetscFunctionBegin;
4950:   PetscCall(PetscObjectSetOptionsPrefix((PetscObject)snes, prefix));
4951:   if (!snes->ksp) PetscCall(SNESGetKSP(snes, &snes->ksp));
4952:   if (snes->linesearch) {
4953:     PetscCall(SNESGetLineSearch(snes, &snes->linesearch));
4954:     PetscCall(PetscObjectSetOptionsPrefix((PetscObject)snes->linesearch, prefix));
4955:   }
4956:   PetscCall(KSPSetOptionsPrefix(snes->ksp, prefix));
4957:   PetscFunctionReturn(PETSC_SUCCESS);
4958: }

4960: /*@C
4961:   SNESAppendOptionsPrefix - Appends to the prefix used for searching for all
4962:   `SNES` options in the database.

4964:   Logically Collective

4966:   Input Parameters:
4967: + snes   - the `SNES` context
4968: - prefix - the prefix to prepend to all option names

4970:   Level: advanced

4972:   Note:
4973:   A hyphen (-) must NOT be given at the beginning of the prefix name.
4974:   The first character of all runtime options is AUTOMATICALLY the hyphen.

4976: .seealso: [](ch_snes), `SNESGetOptionsPrefix()`, `SNESSetOptionsPrefix()`
4977: @*/
4978: PetscErrorCode SNESAppendOptionsPrefix(SNES snes, const char prefix[])
4979: {
4980:   PetscFunctionBegin;
4982:   PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)snes, prefix));
4983:   if (!snes->ksp) PetscCall(SNESGetKSP(snes, &snes->ksp));
4984:   if (snes->linesearch) {
4985:     PetscCall(SNESGetLineSearch(snes, &snes->linesearch));
4986:     PetscCall(PetscObjectAppendOptionsPrefix((PetscObject)snes->linesearch, prefix));
4987:   }
4988:   PetscCall(KSPAppendOptionsPrefix(snes->ksp, prefix));
4989:   PetscFunctionReturn(PETSC_SUCCESS);
4990: }

4992: /*@C
4993:   SNESGetOptionsPrefix - Gets the prefix used for searching for all
4994:   `SNES` options in the database.

4996:   Not Collective

4998:   Input Parameter:
4999: . snes - the `SNES` context

5001:   Output Parameter:
5002: . prefix - pointer to the prefix string used

5004:   Level: advanced

5006:   Fortran Notes:
5007:   The user should pass in a string 'prefix' of
5008:   sufficient length to hold the prefix.

5010: .seealso: [](ch_snes), `SNES`, `SNESSetOptionsPrefix()`, `SNESAppendOptionsPrefix()`
5011: @*/
5012: PetscErrorCode SNESGetOptionsPrefix(SNES snes, const char *prefix[])
5013: {
5014:   PetscFunctionBegin;
5016:   PetscCall(PetscObjectGetOptionsPrefix((PetscObject)snes, prefix));
5017:   PetscFunctionReturn(PETSC_SUCCESS);
5018: }

5020: /*@C
5021:   SNESRegister - Adds a method to the nonlinear solver package.

5023:   Not Collective

5025:   Input Parameters:
5026: + sname    - name of a new user-defined solver
5027: - function - routine to create method context

5029:   Level: advanced

5031:   Note:
5032:   `SNESRegister()` may be called multiple times to add several user-defined solvers.

5034:   Example Usage:
5035: .vb
5036:    SNESRegister("my_solver", MySolverCreate);
5037: .ve

5039:   Then, your solver can be chosen with the procedural interface via
5040: $     SNESSetType(snes, "my_solver")
5041:   or at runtime via the option
5042: $     -snes_type my_solver

5044: .seealso: [](ch_snes), `SNESRegisterAll()`, `SNESRegisterDestroy()`
5045: @*/
5046: PetscErrorCode SNESRegister(const char sname[], PetscErrorCode (*function)(SNES))
5047: {
5048:   PetscFunctionBegin;
5049:   PetscCall(SNESInitializePackage());
5050:   PetscCall(PetscFunctionListAdd(&SNESList, sname, function));
5051:   PetscFunctionReturn(PETSC_SUCCESS);
5052: }

5054: PetscErrorCode SNESTestLocalMin(SNES snes)
5055: {
5056:   PetscInt    N, i, j;
5057:   Vec         u, uh, fh;
5058:   PetscScalar value;
5059:   PetscReal   norm;

5061:   PetscFunctionBegin;
5062:   PetscCall(SNESGetSolution(snes, &u));
5063:   PetscCall(VecDuplicate(u, &uh));
5064:   PetscCall(VecDuplicate(u, &fh));

5066:   /* currently only works for sequential */
5067:   PetscCall(PetscPrintf(PetscObjectComm((PetscObject)snes), "Testing FormFunction() for local min\n"));
5068:   PetscCall(VecGetSize(u, &N));
5069:   for (i = 0; i < N; i++) {
5070:     PetscCall(VecCopy(u, uh));
5071:     PetscCall(PetscPrintf(PetscObjectComm((PetscObject)snes), "i = %" PetscInt_FMT "\n", i));
5072:     for (j = -10; j < 11; j++) {
5073:       value = PetscSign(j) * PetscExpReal(PetscAbs(j) - 10.0);
5074:       PetscCall(VecSetValue(uh, i, value, ADD_VALUES));
5075:       PetscCall(SNESComputeFunction(snes, uh, fh));
5076:       PetscCall(VecNorm(fh, NORM_2, &norm));
5077:       PetscCall(PetscPrintf(PetscObjectComm((PetscObject)snes), "       j norm %" PetscInt_FMT " %18.16e\n", j, (double)norm));
5078:       value = -value;
5079:       PetscCall(VecSetValue(uh, i, value, ADD_VALUES));
5080:     }
5081:   }
5082:   PetscCall(VecDestroy(&uh));
5083:   PetscCall(VecDestroy(&fh));
5084:   PetscFunctionReturn(PETSC_SUCCESS);
5085: }

5087: /*@
5088:   SNESKSPSetUseEW - Sets `SNES` to the use Eisenstat-Walker method for
5089:   computing relative tolerance for linear solvers within an inexact
5090:   Newton method.

5092:   Logically Collective

5094:   Input Parameters:
5095: + snes - `SNES` context
5096: - flag - `PETSC_TRUE` or `PETSC_FALSE`

5098:   Options Database Keys:
5099: + -snes_ksp_ew                       - use Eisenstat-Walker method for determining linear system convergence
5100: . -snes_ksp_ew_version ver           - version of  Eisenstat-Walker method
5101: . -snes_ksp_ew_rtol0 <rtol0>         - Sets rtol0
5102: . -snes_ksp_ew_rtolmax <rtolmax>     - Sets rtolmax
5103: . -snes_ksp_ew_gamma <gamma>         - Sets gamma
5104: . -snes_ksp_ew_alpha <alpha>         - Sets alpha
5105: . -snes_ksp_ew_alpha2 <alpha2>       - Sets alpha2
5106: - -snes_ksp_ew_threshold <threshold> - Sets threshold

5108:   Level: advanced

5110:   Note:
5111:   The default is to use a constant relative tolerance for
5112:   the inner linear solvers.  Alternatively, one can use the
5113:   Eisenstat-Walker method, where the relative convergence tolerance
5114:   is reset at each Newton iteration according progress of the nonlinear
5115:   solver.

5117:   References:
5118: .  - * S. C. Eisenstat and H. F. Walker, "Choosing the forcing terms in an inexact Newton method", SISC 17 (1), pp.16-32, 1996.

5120: .seealso: [](ch_snes), `KSP`, `SNES`, `SNESKSPGetUseEW()`, `SNESKSPGetParametersEW()`, `SNESKSPSetParametersEW()`
5121: @*/
5122: PetscErrorCode SNESKSPSetUseEW(SNES snes, PetscBool flag)
5123: {
5124:   PetscFunctionBegin;
5127:   snes->ksp_ewconv = flag;
5128:   PetscFunctionReturn(PETSC_SUCCESS);
5129: }

5131: /*@
5132:   SNESKSPGetUseEW - Gets if `SNES` is using Eisenstat-Walker method
5133:   for computing relative tolerance for linear solvers within an
5134:   inexact Newton method.

5136:   Not Collective

5138:   Input Parameter:
5139: . snes - `SNES` context

5141:   Output Parameter:
5142: . flag - `PETSC_TRUE` or `PETSC_FALSE`

5144:   Level: advanced

5146: .seealso: [](ch_snes), `SNESKSPSetUseEW()`, `SNESKSPGetParametersEW()`, `SNESKSPSetParametersEW()`
5147: @*/
5148: PetscErrorCode SNESKSPGetUseEW(SNES snes, PetscBool *flag)
5149: {
5150:   PetscFunctionBegin;
5152:   PetscAssertPointer(flag, 2);
5153:   *flag = snes->ksp_ewconv;
5154:   PetscFunctionReturn(PETSC_SUCCESS);
5155: }

5157: /*@
5158:   SNESKSPSetParametersEW - Sets parameters for Eisenstat-Walker
5159:   convergence criteria for the linear solvers within an inexact
5160:   Newton method.

5162:   Logically Collective

5164:   Input Parameters:
5165: + snes      - `SNES` context
5166: . version   - version 1, 2 (default is 2), 3 or 4
5167: . rtol_0    - initial relative tolerance (0 <= rtol_0 < 1)
5168: . rtol_max  - maximum relative tolerance (0 <= rtol_max < 1)
5169: . gamma     - multiplicative factor for version 2 rtol computation
5170:              (0 <= gamma2 <= 1)
5171: . alpha     - power for version 2 rtol computation (1 < alpha <= 2)
5172: . alpha2    - power for safeguard
5173: - threshold - threshold for imposing safeguard (0 < threshold < 1)

5175:   Level: advanced

5177:   Notes:
5178:   Version 3 was contributed by Luis Chacon, June 2006.

5180:   Use `PETSC_DEFAULT` to retain the default for any of the parameters.

5182: .seealso: [](ch_snes), `SNES`, `SNESKSPSetUseEW()`, `SNESKSPGetUseEW()`, `SNESKSPGetParametersEW()`
5183: @*/
5184: PetscErrorCode SNESKSPSetParametersEW(SNES snes, PetscInt version, PetscReal rtol_0, PetscReal rtol_max, PetscReal gamma, PetscReal alpha, PetscReal alpha2, PetscReal threshold)
5185: {
5186:   SNESKSPEW *kctx;

5188:   PetscFunctionBegin;
5190:   kctx = (SNESKSPEW *)snes->kspconvctx;
5191:   PetscCheck(kctx, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "No Eisenstat-Walker context existing");

5200:   if (version != PETSC_DEFAULT) kctx->version = version;
5201:   if (rtol_0 != (PetscReal)PETSC_DEFAULT) kctx->rtol_0 = rtol_0;
5202:   if (rtol_max != (PetscReal)PETSC_DEFAULT) kctx->rtol_max = rtol_max;
5203:   if (gamma != (PetscReal)PETSC_DEFAULT) kctx->gamma = gamma;
5204:   if (alpha != (PetscReal)PETSC_DEFAULT) kctx->alpha = alpha;
5205:   if (alpha2 != (PetscReal)PETSC_DEFAULT) kctx->alpha2 = alpha2;
5206:   if (threshold != (PetscReal)PETSC_DEFAULT) kctx->threshold = threshold;

5208:   PetscCheck(kctx->version >= 1 && kctx->version <= 4, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Only versions 1 to 4 are supported: %" PetscInt_FMT, kctx->version);
5209:   PetscCheck(kctx->rtol_0 >= 0.0 && kctx->rtol_0 < 1.0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "0.0 <= rtol_0 < 1.0: %g", (double)kctx->rtol_0);
5210:   PetscCheck(kctx->rtol_max >= 0.0 && kctx->rtol_max < 1.0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "0.0 <= rtol_max (%g) < 1.0", (double)kctx->rtol_max);
5211:   PetscCheck(kctx->gamma >= 0.0 && kctx->gamma <= 1.0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "0.0 <= gamma (%g) <= 1.0", (double)kctx->gamma);
5212:   PetscCheck(kctx->alpha > 1.0 && kctx->alpha <= 2.0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "1.0 < alpha (%g) <= 2.0", (double)kctx->alpha);
5213:   PetscCheck(kctx->threshold > 0.0 && kctx->threshold < 1.0, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "0.0 < threshold (%g) < 1.0", (double)kctx->threshold);
5214:   PetscFunctionReturn(PETSC_SUCCESS);
5215: }

5217: /*@
5218:   SNESKSPGetParametersEW - Gets parameters for Eisenstat-Walker
5219:   convergence criteria for the linear solvers within an inexact
5220:   Newton method.

5222:   Not Collective

5224:   Input Parameter:
5225: . snes - `SNES` context

5227:   Output Parameters:
5228: + version   - version 1, 2 (default is 2), 3 or 4
5229: . rtol_0    - initial relative tolerance (0 <= rtol_0 < 1)
5230: . rtol_max  - maximum relative tolerance (0 <= rtol_max < 1)
5231: . gamma     - multiplicative factor for version 2 rtol computation (0 <= gamma2 <= 1)
5232: . alpha     - power for version 2 rtol computation (1 < alpha <= 2)
5233: . alpha2    - power for safeguard
5234: - threshold - threshold for imposing safeguard (0 < threshold < 1)

5236:   Level: advanced

5238: .seealso: [](ch_snes), `SNES`, `SNESKSPSetUseEW()`, `SNESKSPGetUseEW()`, `SNESKSPSetParametersEW()`
5239: @*/
5240: PetscErrorCode SNESKSPGetParametersEW(SNES snes, PetscInt *version, PetscReal *rtol_0, PetscReal *rtol_max, PetscReal *gamma, PetscReal *alpha, PetscReal *alpha2, PetscReal *threshold)
5241: {
5242:   SNESKSPEW *kctx;

5244:   PetscFunctionBegin;
5246:   kctx = (SNESKSPEW *)snes->kspconvctx;
5247:   PetscCheck(kctx, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "No Eisenstat-Walker context existing");
5248:   if (version) *version = kctx->version;
5249:   if (rtol_0) *rtol_0 = kctx->rtol_0;
5250:   if (rtol_max) *rtol_max = kctx->rtol_max;
5251:   if (gamma) *gamma = kctx->gamma;
5252:   if (alpha) *alpha = kctx->alpha;
5253:   if (alpha2) *alpha2 = kctx->alpha2;
5254:   if (threshold) *threshold = kctx->threshold;
5255:   PetscFunctionReturn(PETSC_SUCCESS);
5256: }

5258: PetscErrorCode KSPPreSolve_SNESEW(KSP ksp, Vec b, Vec x, void *ctx)
5259: {
5260:   SNES       snes = (SNES)ctx;
5261:   SNESKSPEW *kctx = (SNESKSPEW *)snes->kspconvctx;
5262:   PetscReal  rtol = PETSC_DEFAULT, stol;

5264:   PetscFunctionBegin;
5265:   if (!snes->ksp_ewconv) PetscFunctionReturn(PETSC_SUCCESS);
5266:   if (!snes->iter) {
5267:     rtol = kctx->rtol_0; /* first time in, so use the original user rtol */
5268:     PetscCall(VecNorm(snes->vec_func, NORM_2, &kctx->norm_first));
5269:   } else {
5270:     PetscCheck(kctx->version >= 1 && kctx->version <= 4, PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Only versions 1-4 are supported: %" PetscInt_FMT, kctx->version);
5271:     if (kctx->version == 1) {
5272:       rtol = PetscAbsReal(snes->norm - kctx->lresid_last) / kctx->norm_last;
5273:       stol = PetscPowReal(kctx->rtol_last, kctx->alpha2);
5274:       if (stol > kctx->threshold) rtol = PetscMax(rtol, stol);
5275:     } else if (kctx->version == 2) {
5276:       rtol = kctx->gamma * PetscPowReal(snes->norm / kctx->norm_last, kctx->alpha);
5277:       stol = kctx->gamma * PetscPowReal(kctx->rtol_last, kctx->alpha);
5278:       if (stol > kctx->threshold) rtol = PetscMax(rtol, stol);
5279:     } else if (kctx->version == 3) { /* contributed by Luis Chacon, June 2006. */
5280:       rtol = kctx->gamma * PetscPowReal(snes->norm / kctx->norm_last, kctx->alpha);
5281:       /* safeguard: avoid sharp decrease of rtol */
5282:       stol = kctx->gamma * PetscPowReal(kctx->rtol_last, kctx->alpha);
5283:       stol = PetscMax(rtol, stol);
5284:       rtol = PetscMin(kctx->rtol_0, stol);
5285:       /* safeguard: avoid oversolving */
5286:       stol = kctx->gamma * (kctx->norm_first * snes->rtol) / snes->norm;
5287:       stol = PetscMax(rtol, stol);
5288:       rtol = PetscMin(kctx->rtol_0, stol);
5289:     } else /* if (kctx->version == 4) */ {
5290:       /* H.-B. An et al. Journal of Computational and Applied Mathematics 200 (2007) 47-60 */
5291:       PetscReal ared = PetscAbsReal(kctx->norm_last - snes->norm);
5292:       PetscReal pred = PetscAbsReal(kctx->norm_last - kctx->lresid_last);
5293:       PetscReal rk   = ared / pred;
5294:       if (rk < kctx->v4_p1) rtol = 1. - 2. * kctx->v4_p1;
5295:       else if (rk < kctx->v4_p2) rtol = kctx->rtol_last;
5296:       else if (rk < kctx->v4_p3) rtol = kctx->v4_m1 * kctx->rtol_last;
5297:       else rtol = kctx->v4_m2 * kctx->rtol_last;

5299:       if (kctx->rtol_last_2 > kctx->v4_m3 && kctx->rtol_last > kctx->v4_m3 && kctx->rk_last_2 < kctx->v4_p1 && kctx->rk_last < kctx->v4_p1) rtol = kctx->v4_m4 * kctx->rtol_last;
5300:       kctx->rtol_last_2 = kctx->rtol_last;
5301:       kctx->rk_last_2   = kctx->rk_last;
5302:       kctx->rk_last     = rk;
5303:     }
5304:   }
5305:   /* safeguard: avoid rtol greater than rtol_max */
5306:   rtol = PetscMin(rtol, kctx->rtol_max);
5307:   PetscCall(KSPSetTolerances(ksp, rtol, PETSC_DEFAULT, PETSC_DEFAULT, PETSC_DEFAULT));
5308:   PetscCall(PetscInfo(snes, "iter %" PetscInt_FMT ", Eisenstat-Walker (version %" PetscInt_FMT ") KSP rtol=%g\n", snes->iter, kctx->version, (double)rtol));
5309:   PetscFunctionReturn(PETSC_SUCCESS);
5310: }

5312: PetscErrorCode KSPPostSolve_SNESEW(KSP ksp, Vec b, Vec x, void *ctx)
5313: {
5314:   SNES       snes = (SNES)ctx;
5315:   SNESKSPEW *kctx = (SNESKSPEW *)snes->kspconvctx;
5316:   PCSide     pcside;
5317:   Vec        lres;

5319:   PetscFunctionBegin;
5320:   if (!snes->ksp_ewconv) PetscFunctionReturn(PETSC_SUCCESS);
5321:   PetscCall(KSPGetTolerances(ksp, &kctx->rtol_last, NULL, NULL, NULL));
5322:   kctx->norm_last = snes->norm;
5323:   if (kctx->version == 1 || kctx->version == 4) {
5324:     PC        pc;
5325:     PetscBool getRes;

5327:     PetscCall(KSPGetPC(ksp, &pc));
5328:     PetscCall(PetscObjectTypeCompare((PetscObject)pc, PCNONE, &getRes));
5329:     if (!getRes) {
5330:       KSPNormType normtype;

5332:       PetscCall(KSPGetNormType(ksp, &normtype));
5333:       getRes = (PetscBool)(normtype == KSP_NORM_UNPRECONDITIONED);
5334:     }
5335:     PetscCall(KSPGetPCSide(ksp, &pcside));
5336:     if (pcside == PC_RIGHT || getRes) { /* KSP residual is true linear residual */
5337:       PetscCall(KSPGetResidualNorm(ksp, &kctx->lresid_last));
5338:     } else {
5339:       /* KSP residual is preconditioned residual */
5340:       /* compute true linear residual norm */
5341:       Mat J;
5342:       PetscCall(KSPGetOperators(ksp, &J, NULL));
5343:       PetscCall(VecDuplicate(b, &lres));
5344:       PetscCall(MatMult(J, x, lres));
5345:       PetscCall(VecAYPX(lres, -1.0, b));
5346:       PetscCall(VecNorm(lres, NORM_2, &kctx->lresid_last));
5347:       PetscCall(VecDestroy(&lres));
5348:     }
5349:   }
5350:   PetscFunctionReturn(PETSC_SUCCESS);
5351: }

5353: /*@
5354:   SNESGetKSP - Returns the `KSP` context for a `SNES` solver.

5356:   Not Collective, but if snes is parallel, then ksp is parallel

5358:   Input Parameter:
5359: . snes - the `SNES` context

5361:   Output Parameter:
5362: . ksp - the `KSP` context

5364:   Level: beginner

5366:   Notes:
5367:   The user can then directly manipulate the `KSP` context to set various
5368:   options, etc.  Likewise, the user can then extract and manipulate the
5369:   `PC` contexts as well.

5371:   Some `SNESType`s do not use a `KSP` but a `KSP` is still returned by this function

5373: .seealso: [](ch_snes), `SNES`, `KSP`, `PC`, `KSPGetPC()`, `SNESCreate()`, `KSPCreate()`, `SNESSetKSP()`
5374: @*/
5375: PetscErrorCode SNESGetKSP(SNES snes, KSP *ksp)
5376: {
5377:   PetscFunctionBegin;
5379:   PetscAssertPointer(ksp, 2);

5381:   if (!snes->ksp) {
5382:     PetscCall(KSPCreate(PetscObjectComm((PetscObject)snes), &snes->ksp));
5383:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)snes->ksp, (PetscObject)snes, 1));

5385:     PetscCall(KSPSetPreSolve(snes->ksp, KSPPreSolve_SNESEW, snes));
5386:     PetscCall(KSPSetPostSolve(snes->ksp, KSPPostSolve_SNESEW, snes));

5388:     PetscCall(KSPMonitorSetFromOptions(snes->ksp, "-snes_monitor_ksp", "snes_preconditioned_residual", snes));
5389:     PetscCall(PetscObjectSetOptions((PetscObject)snes->ksp, ((PetscObject)snes)->options));
5390:   }
5391:   *ksp = snes->ksp;
5392:   PetscFunctionReturn(PETSC_SUCCESS);
5393: }

5395: #include <petsc/private/dmimpl.h>
5396: /*@
5397:   SNESSetDM - Sets the `DM` that may be used by some nonlinear solvers or their underlying preconditioners

5399:   Logically Collective

5401:   Input Parameters:
5402: + snes - the nonlinear solver context
5403: - dm   - the dm, cannot be `NULL`

5405:   Level: intermediate

5407:   Note:
5408:   A `DM` can only be used for solving one problem at a time because information about the problem is stored on the `DM`,
5409:   even when not using interfaces like `DMSNESSetFunction()`.  Use `DMClone()` to get a distinct `DM` when solving different
5410:   problems using the same function space.

5412: .seealso: [](ch_snes), `DM`, `SNESGetDM()`, `KSPSetDM()`, `KSPGetDM()`
5413: @*/
5414: PetscErrorCode SNESSetDM(SNES snes, DM dm)
5415: {
5416:   KSP    ksp;
5417:   DMSNES sdm;

5419:   PetscFunctionBegin;
5422:   PetscCall(PetscObjectReference((PetscObject)dm));
5423:   if (snes->dm) { /* Move the DMSNES context over to the new DM unless the new DM already has one */
5424:     if (snes->dm->dmsnes && !dm->dmsnes) {
5425:       PetscCall(DMCopyDMSNES(snes->dm, dm));
5426:       PetscCall(DMGetDMSNES(snes->dm, &sdm));
5427:       if (sdm->originaldm == snes->dm) sdm->originaldm = dm; /* Grant write privileges to the replacement DM */
5428:     }
5429:     PetscCall(DMCoarsenHookRemove(snes->dm, DMCoarsenHook_SNESVecSol, DMRestrictHook_SNESVecSol, snes));
5430:     PetscCall(DMDestroy(&snes->dm));
5431:   }
5432:   snes->dm     = dm;
5433:   snes->dmAuto = PETSC_FALSE;

5435:   PetscCall(SNESGetKSP(snes, &ksp));
5436:   PetscCall(KSPSetDM(ksp, dm));
5437:   PetscCall(KSPSetDMActive(ksp, PETSC_FALSE));
5438:   if (snes->npc) {
5439:     PetscCall(SNESSetDM(snes->npc, snes->dm));
5440:     PetscCall(SNESSetNPCSide(snes, snes->npcside));
5441:   }
5442:   PetscFunctionReturn(PETSC_SUCCESS);
5443: }

5445: /*@
5446:   SNESGetDM - Gets the `DM` that may be used by some preconditioners

5448:   Not Collective but dm obtained is parallel on snes

5450:   Input Parameter:
5451: . snes - the preconditioner context

5453:   Output Parameter:
5454: . dm - the dm

5456:   Level: intermediate

5458: .seealso: [](ch_snes), `DM`, `SNESSetDM()`, `KSPSetDM()`, `KSPGetDM()`
5459: @*/
5460: PetscErrorCode SNESGetDM(SNES snes, DM *dm)
5461: {
5462:   PetscFunctionBegin;
5464:   if (!snes->dm) {
5465:     PetscCall(DMShellCreate(PetscObjectComm((PetscObject)snes), &snes->dm));
5466:     snes->dmAuto = PETSC_TRUE;
5467:   }
5468:   *dm = snes->dm;
5469:   PetscFunctionReturn(PETSC_SUCCESS);
5470: }

5472: /*@
5473:   SNESSetNPC - Sets the nonlinear preconditioner to be used.

5475:   Collective

5477:   Input Parameters:
5478: + snes - iterative context obtained from `SNESCreate()`
5479: - npc  - the preconditioner object

5481:   Level: developer

5483:   Notes:
5484:   Use `SNESGetNPC()` to retrieve the preconditioner context (for example,
5485:   to configure it using the API).

5487:   Only some `SNESType` can use a nonlinear preconditioner

5489: .seealso: [](ch_snes), `SNESNGS`, `SNESFAS`, `SNESGetNPC()`, `SNESHasNPC()`
5490: @*/
5491: PetscErrorCode SNESSetNPC(SNES snes, SNES npc)
5492: {
5493:   PetscFunctionBegin;
5496:   PetscCheckSameComm(snes, 1, npc, 2);
5497:   PetscCall(PetscObjectReference((PetscObject)npc));
5498:   PetscCall(SNESDestroy(&snes->npc));
5499:   snes->npc = npc;
5500:   PetscFunctionReturn(PETSC_SUCCESS);
5501: }

5503: /*@
5504:   SNESGetNPC - Gets a nonlinear preconditioning solver SNES` to be used to precondition the original nonlinear solver.

5506:   Not Collective; but any changes to the obtained the npc object must be applied collectively

5508:   Input Parameter:
5509: . snes - iterative context obtained from `SNESCreate()`

5511:   Output Parameter:
5512: . pc - preconditioner context

5514:   Options Database Key:
5515: . -npc_snes_type <type> - set the type of the `SNES` to use as the nonlinear preconditioner

5517:   Level: developer

5519:   Notes:
5520:   If a `SNES` was previously set with `SNESSetNPC()` then that value is returned, otherwise a new `SNES` object is created.

5522:   The (preconditioner) `SNES` returned automatically inherits the same nonlinear function and Jacobian supplied to the original
5523:   `SNES`

5525: .seealso: [](ch_snes), `SNESSetNPC()`, `SNESHasNPC()`, `SNES`, `SNESCreate()`
5526: @*/
5527: PetscErrorCode SNESGetNPC(SNES snes, SNES *pc)
5528: {
5529:   const char *optionsprefix;

5531:   PetscFunctionBegin;
5533:   PetscAssertPointer(pc, 2);
5534:   if (!snes->npc) {
5535:     void *ctx;

5537:     PetscCall(SNESCreate(PetscObjectComm((PetscObject)snes), &snes->npc));
5538:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)snes->npc, (PetscObject)snes, 1));
5539:     PetscCall(SNESGetOptionsPrefix(snes, &optionsprefix));
5540:     PetscCall(SNESSetOptionsPrefix(snes->npc, optionsprefix));
5541:     PetscCall(SNESAppendOptionsPrefix(snes->npc, "npc_"));
5542:     PetscCall(SNESGetApplicationContext(snes, &ctx));
5543:     PetscCall(SNESSetApplicationContext(snes->npc, ctx));
5544:     PetscCall(SNESSetCountersReset(snes->npc, PETSC_FALSE));
5545:   }
5546:   *pc = snes->npc;
5547:   PetscFunctionReturn(PETSC_SUCCESS);
5548: }

5550: /*@
5551:   SNESHasNPC - Returns whether a nonlinear preconditioner exists

5553:   Not Collective

5555:   Input Parameter:
5556: . snes - iterative context obtained from `SNESCreate()`

5558:   Output Parameter:
5559: . has_npc - whether the `SNES` has an NPC or not

5561:   Level: developer

5563: .seealso: [](ch_snes), `SNESSetNPC()`, `SNESGetNPC()`
5564: @*/
5565: PetscErrorCode SNESHasNPC(SNES snes, PetscBool *has_npc)
5566: {
5567:   PetscFunctionBegin;
5569:   *has_npc = (PetscBool)(snes->npc ? PETSC_TRUE : PETSC_FALSE);
5570:   PetscFunctionReturn(PETSC_SUCCESS);
5571: }

5573: /*@
5574:   SNESSetNPCSide - Sets the preconditioning side.

5576:   Logically Collective

5578:   Input Parameter:
5579: . snes - iterative context obtained from `SNESCreate()`

5581:   Output Parameter:
5582: . side - the preconditioning side, where side is one of
5583: .vb
5584:       PC_LEFT - left preconditioning
5585:       PC_RIGHT - right preconditioning (default for most nonlinear solvers)
5586: .ve

5588:   Options Database Key:
5589: . -snes_npc_side <right,left> - nonlinear preconditioner side

5591:   Level: intermediate

5593:   Note:
5594:   `SNESNRICHARDSON` and `SNESNCG` only support left preconditioning.

5596: .seealso: [](ch_snes), `SNESType`, `SNESGetNPCSide()`, `KSPSetPCSide()`
5597: @*/
5598: PetscErrorCode SNESSetNPCSide(SNES snes, PCSide side)
5599: {
5600:   PetscFunctionBegin;
5603:   if (side == PC_SIDE_DEFAULT) side = PC_RIGHT;
5604:   PetscCheck((side == PC_LEFT) || (side == PC_RIGHT), PetscObjectComm((PetscObject)snes), PETSC_ERR_ARG_WRONG, "Only PC_LEFT and PC_RIGHT are supported");
5605:   snes->npcside = side;
5606:   PetscFunctionReturn(PETSC_SUCCESS);
5607: }

5609: /*@
5610:   SNESGetNPCSide - Gets the preconditioning side.

5612:   Not Collective

5614:   Input Parameter:
5615: . snes - iterative context obtained from `SNESCreate()`

5617:   Output Parameter:
5618: . side - the preconditioning side, where side is one of
5619: .vb
5620:       `PC_LEFT` - left preconditioning
5621:       `PC_RIGHT` - right preconditioning (default for most nonlinear solvers)
5622: .ve

5624:   Level: intermediate

5626: .seealso: [](ch_snes), `SNES`, `SNESSetNPCSide()`, `KSPGetPCSide()`
5627: @*/
5628: PetscErrorCode SNESGetNPCSide(SNES snes, PCSide *side)
5629: {
5630:   PetscFunctionBegin;
5632:   PetscAssertPointer(side, 2);
5633:   *side = snes->npcside;
5634:   PetscFunctionReturn(PETSC_SUCCESS);
5635: }

5637: /*@
5638:   SNESSetLineSearch - Sets the linesearch on the `SNES` instance.

5640:   Collective

5642:   Input Parameters:
5643: + snes       - iterative context obtained from `SNESCreate()`
5644: - linesearch - the linesearch object

5646:   Level: developer

5648:   Note:
5649:   Use `SNESGetLineSearch()` to retrieve the preconditioner context (for example,
5650:   to configure it using the API).

5652: .seealso: [](ch_snes), `SNESGetLineSearch()`
5653: @*/
5654: PetscErrorCode SNESSetLineSearch(SNES snes, SNESLineSearch linesearch)
5655: {
5656:   PetscFunctionBegin;
5659:   PetscCheckSameComm(snes, 1, linesearch, 2);
5660:   PetscCall(PetscObjectReference((PetscObject)linesearch));
5661:   PetscCall(SNESLineSearchDestroy(&snes->linesearch));

5663:   snes->linesearch = linesearch;

5665:   PetscFunctionReturn(PETSC_SUCCESS);
5666: }

5668: /*@
5669:   SNESGetLineSearch - Returns the line search context set with `SNESSetLineSearch()`
5670:   or creates a default line search instance associated with the `SNES` and returns it.

5672:   Not Collective

5674:   Input Parameter:
5675: . snes - iterative context obtained from `SNESCreate()`

5677:   Output Parameter:
5678: . linesearch - linesearch context

5680:   Level: beginner

5682: .seealso: [](ch_snes), `SNESLineSearch`, `SNESSetLineSearch()`, `SNESLineSearchCreate()`
5683: @*/
5684: PetscErrorCode SNESGetLineSearch(SNES snes, SNESLineSearch *linesearch)
5685: {
5686:   const char *optionsprefix;

5688:   PetscFunctionBegin;
5690:   PetscAssertPointer(linesearch, 2);
5691:   if (!snes->linesearch) {
5692:     PetscCall(SNESGetOptionsPrefix(snes, &optionsprefix));
5693:     PetscCall(SNESLineSearchCreate(PetscObjectComm((PetscObject)snes), &snes->linesearch));
5694:     PetscCall(SNESLineSearchSetSNES(snes->linesearch, snes));
5695:     PetscCall(SNESLineSearchAppendOptionsPrefix(snes->linesearch, optionsprefix));
5696:     PetscCall(PetscObjectIncrementTabLevel((PetscObject)snes->linesearch, (PetscObject)snes, 1));
5697:   }
5698:   *linesearch = snes->linesearch;
5699:   PetscFunctionReturn(PETSC_SUCCESS);
5700: }