Actual source code: ex28.c
1: static char help[] = "Test sequential USFFT interface on a 3-dof field over a uniform DMDA and compares to the result of FFTW acting on a split version of the field\n\n";
3: /*
4: Compiling the code:
5: This code uses the complex numbers version of PETSc and the FFTW package, so configure
6: must be run to enable these.
8: */
10: #define DOF 3
12: #include <petscmat.h>
13: #include <petscdm.h>
14: #include <petscdmda.h>
15: int main(int argc, char **args)
16: {
17: typedef enum {
18: RANDOM,
19: CONSTANT,
20: TANH,
21: NUM_FUNCS
22: } FuncType;
23: const char *funcNames[NUM_FUNCS] = {"random", "constant", "tanh"};
24: Mat A, AA;
25: PetscMPIInt size;
26: PetscInt N, i, stencil = 1, dof = 3;
27: PetscInt dim[3] = {10, 10, 10}, ndim = 3;
28: Vec coords, x, y, z, xx, yy, zz;
29: Vec xxsplit[DOF], yysplit[DOF], zzsplit[DOF];
30: PetscReal h[3];
31: PetscScalar s;
32: PetscRandom rdm;
33: PetscReal norm, enorm;
34: PetscInt func, ii;
35: FuncType function = TANH;
36: DM da, da1, coordsda;
37: PetscBool view_x = PETSC_FALSE, view_y = PETSC_FALSE, view_z = PETSC_FALSE;
39: PetscFunctionBeginUser;
40: PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
41: PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
42: PetscCheck(size == 1, PETSC_COMM_WORLD, PETSC_ERR_SUP, "This is a uniprocessor example only!");
43: PetscOptionsBegin(PETSC_COMM_WORLD, NULL, "USFFT Options", "ex27");
44: PetscCall(PetscOptionsEList("-function", "Function type", "ex27", funcNames, NUM_FUNCS, funcNames[function], &func, NULL));
45: function = (FuncType)func;
46: PetscOptionsEnd();
47: PetscCall(PetscOptionsGetBool(NULL, NULL, "-view_x", &view_x, NULL));
48: PetscCall(PetscOptionsGetBool(NULL, NULL, "-view_y", &view_y, NULL));
49: PetscCall(PetscOptionsGetBool(NULL, NULL, "-view_z", &view_z, NULL));
50: PetscCall(PetscOptionsGetIntArray(NULL, NULL, "-dim", dim, &ndim, NULL));
52: /* DMDA with the correct fiber dimension */
53: PetscCall(DMDACreate3d(PETSC_COMM_SELF, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DMDA_STENCIL_STAR, dim[0], dim[1], dim[2], PETSC_DECIDE, PETSC_DECIDE, PETSC_DECIDE, dof, stencil, NULL, NULL, NULL, &da));
54: PetscCall(DMSetFromOptions(da));
55: PetscCall(DMSetUp(da));
56: /* DMDA with fiber dimension 1 for split fields */
57: PetscCall(DMDACreate3d(PETSC_COMM_SELF, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DMDA_STENCIL_STAR, dim[0], dim[1], dim[2], PETSC_DECIDE, PETSC_DECIDE, PETSC_DECIDE, 1, stencil, NULL, NULL, NULL, &da1));
58: PetscCall(DMSetFromOptions(da1));
59: PetscCall(DMSetUp(da1));
61: /* Coordinates */
62: PetscCall(DMGetCoordinateDM(da, &coordsda));
63: PetscCall(DMGetGlobalVector(coordsda, &coords));
64: PetscCall(PetscObjectSetName((PetscObject)coords, "Grid coordinates"));
65: for (i = 0, N = 1; i < 3; i++) {
66: h[i] = 1.0 / dim[i];
67: PetscScalar *a;
68: PetscCall(VecGetArray(coords, &a));
69: PetscInt j, k, n = 0;
70: for (i = 0; i < 3; ++i) {
71: for (j = 0; j < dim[i]; ++j) {
72: for (k = 0; k < 3; ++k) {
73: a[n] = j * h[i]; /* coordinate along the j-th point in the i-th dimension */
74: ++n;
75: }
76: }
77: }
78: PetscCall(VecRestoreArray(coords, &a));
79: }
80: PetscCall(DMSetCoordinates(da, coords));
81: PetscCall(VecDestroy(&coords));
83: /* Work vectors */
84: PetscCall(DMGetGlobalVector(da, &x));
85: PetscCall(PetscObjectSetName((PetscObject)x, "Real space vector"));
86: PetscCall(DMGetGlobalVector(da, &xx));
87: PetscCall(PetscObjectSetName((PetscObject)xx, "Real space vector"));
88: PetscCall(DMGetGlobalVector(da, &y));
89: PetscCall(PetscObjectSetName((PetscObject)y, "USFFT frequency space vector"));
90: PetscCall(DMGetGlobalVector(da, &yy));
91: PetscCall(PetscObjectSetName((PetscObject)yy, "FFTW frequency space vector"));
92: PetscCall(DMGetGlobalVector(da, &z));
93: PetscCall(PetscObjectSetName((PetscObject)z, "USFFT reconstructed vector"));
94: PetscCall(DMGetGlobalVector(da, &zz));
95: PetscCall(PetscObjectSetName((PetscObject)zz, "FFTW reconstructed vector"));
96: /* Split vectors for FFTW */
97: for (ii = 0; ii < 3; ++ii) {
98: PetscCall(DMGetGlobalVector(da1, &xxsplit[ii]));
99: PetscCall(PetscObjectSetName((PetscObject)xxsplit[ii], "Real space split vector"));
100: PetscCall(DMGetGlobalVector(da1, &yysplit[ii]));
101: PetscCall(PetscObjectSetName((PetscObject)yysplit[ii], "FFTW frequency space split vector"));
102: PetscCall(DMGetGlobalVector(da1, &zzsplit[ii]));
103: PetscCall(PetscObjectSetName((PetscObject)zzsplit[ii], "FFTW reconstructed split vector"));
104: }
106: PetscCall(PetscPrintf(PETSC_COMM_SELF, "%3-" PetscInt_FMT ": USFFT on vector of "));
107: for (i = 0, N = 1; i < 3; i++) {
108: PetscCall(PetscPrintf(PETSC_COMM_SELF, "dim[%d] = %d ", i, dim[i]));
109: N *= dim[i];
110: }
111: PetscCall(PetscPrintf(PETSC_COMM_SELF, "; total size %d \n", N));
113: if (function == RANDOM) {
114: PetscCall(PetscRandomCreate(PETSC_COMM_SELF, &rdm));
115: PetscCall(PetscRandomSetFromOptions(rdm));
116: PetscCall(VecSetRandom(x, rdm));
117: PetscCall(PetscRandomDestroy(&rdm));
118: } else if (function == CONSTANT) {
119: PetscCall(VecSet(x, 1.0));
120: } else if (function == TANH) {
121: PetscScalar *a;
122: PetscCall(VecGetArray(x, &a));
123: PetscInt j, k = 0;
124: for (i = 0; i < 3; ++i) {
125: for (j = 0; j < dim[i]; ++j) {
126: a[k] = tanh((j - dim[i] / 2.0) * (10.0 / dim[i]));
127: ++k;
128: }
129: }
130: PetscCall(VecRestoreArray(x, &a));
131: }
132: if (view_x) PetscCall(VecView(x, PETSC_VIEWER_STDOUT_WORLD));
133: PetscCall(VecCopy(x, xx));
134: /* Split xx */
135: PetscCall(VecStrideGatherAll(xx, xxsplit, INSERT_VALUES)); /*YES! 'Gather' means 'split' (or maybe 'scatter'?)! */
137: PetscCall(VecNorm(x, NORM_2, &norm));
138: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|x|_2 = %g\n", norm));
140: /* create USFFT object */
141: PetscCall(MatCreateSeqUSFFT(da, da, &A));
142: /* create FFTW object */
143: PetscCall(MatCreateSeqFFTW(PETSC_COMM_SELF, 3, dim, &AA));
145: /* apply USFFT and FFTW FORWARD "preemptively", so the fftw_plans can be reused on different vectors */
146: PetscCall(MatMult(A, x, z));
147: for (ii = 0; ii < 3; ++ii) PetscCall(MatMult(AA, xxsplit[ii], zzsplit[ii]));
148: /* Now apply USFFT and FFTW forward several (3) times */
149: for (i = 0; i < 3; ++i) {
150: PetscCall(MatMult(A, x, y));
151: for (ii = 0; ii < 3; ++ii) PetscCall(MatMult(AA, xxsplit[ii], yysplit[ii]));
152: PetscCall(MatMultTranspose(A, y, z));
153: for (ii = 0; ii < 3; ++ii) PetscCall(MatMult(AA, yysplit[ii], zzsplit[ii]));
154: }
155: /* Unsplit yy */
156: PetscCall(VecStrideScatterAll(yysplit, yy, INSERT_VALUES)); /*YES! 'Scatter' means 'collect' (or maybe 'gather'?)! */
157: /* Unsplit zz */
158: PetscCall(VecStrideScatterAll(zzsplit, zz, INSERT_VALUES)); /*YES! 'Scatter' means 'collect' (or maybe 'gather'?)! */
160: if (view_y) {
161: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "y = \n"));
162: PetscCall(VecView(y, PETSC_VIEWER_STDOUT_WORLD));
163: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "yy = \n"));
164: PetscCall(VecView(yy, PETSC_VIEWER_STDOUT_WORLD));
165: }
167: if (view_z) {
168: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "z = \n"));
169: PetscCall(VecView(z, PETSC_VIEWER_STDOUT_WORLD));
170: PetscCall(PetscPrintf(PETSC_COMM_WORLD, "zz = \n"));
171: PetscCall(VecView(zz, PETSC_VIEWER_STDOUT_WORLD));
172: }
174: /* compare x and z. USFFT computes an unnormalized DFT, thus z = N*x */
175: s = 1.0 / (PetscReal)N;
176: PetscCall(VecScale(z, s));
177: PetscCall(VecAXPY(x, -1.0, z));
178: PetscCall(VecNorm(x, NORM_1, &enorm));
179: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|x-z| = %g\n", enorm));
181: /* compare xx and zz. FFTW computes an unnormalized DFT, thus zz = N*x */
182: s = 1.0 / (PetscReal)N;
183: PetscCall(VecScale(zz, s));
184: PetscCall(VecAXPY(xx, -1.0, zz));
185: PetscCall(VecNorm(xx, NORM_1, &enorm));
186: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|xx-zz| = %g\n", enorm));
188: /* compare y and yy: USFFT and FFTW results*/
189: PetscCall(VecNorm(y, NORM_2, &norm));
190: PetscCall(VecAXPY(y, -1.0, yy));
191: PetscCall(VecNorm(y, NORM_1, &enorm));
192: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|y|_2 = %g\n", norm));
193: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|y-yy| = %g\n", enorm));
195: /* compare z and zz: USFFT and FFTW results*/
196: PetscCall(VecNorm(z, NORM_2, &norm));
197: PetscCall(VecAXPY(z, -1.0, zz));
198: PetscCall(VecNorm(z, NORM_1, &enorm));
199: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|z|_2 = %g\n", norm));
200: PetscCall(PetscPrintf(PETSC_COMM_SELF, "|z-zz| = %g\n", enorm));
202: /* free spaces */
203: PetscCall(DMRestoreGlobalVector(da, &x));
204: PetscCall(DMRestoreGlobalVector(da, &xx));
205: PetscCall(DMRestoreGlobalVector(da, &y));
206: PetscCall(DMRestoreGlobalVector(da, &yy));
207: PetscCall(DMRestoreGlobalVector(da, &z));
208: PetscCall(DMRestoreGlobalVector(da, &zz));
210: PetscCall(PetscFinalize());
211: return 0;
212: }