Actual source code: ex4.c
1: static char help[] = "Demonstrates the use of fast Richardson for SOR. And tests\n\
2: the MatSOR() routines.\n\n";
4: #include <petscpc.h>
6: int main(int argc, char **args)
7: {
8: Mat mat;
9: Vec b, u;
10: PC pc;
11: PetscInt n = 5, i, col[3];
12: PetscScalar value[3];
14: PetscFunctionBeginUser;
15: PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
16: /* Create vectors */
17: PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &b));
18: PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &u));
20: /* Create and assemble matrix */
21: PetscCall(MatCreateSeqDense(PETSC_COMM_SELF, n, n, NULL, &mat));
22: value[0] = -1.0;
23: value[1] = 2.0;
24: value[2] = -1.0;
25: for (i = 1; i < n - 1; i++) {
26: col[0] = i - 1;
27: col[1] = i;
28: col[2] = i + 1;
29: PetscCall(MatSetValues(mat, 1, &i, 3, col, value, INSERT_VALUES));
30: }
31: i = n - 1;
32: col[0] = n - 2;
33: col[1] = n - 1;
34: PetscCall(MatSetValues(mat, 1, &i, 2, col, value, INSERT_VALUES));
35: i = 0;
36: col[0] = 0;
37: col[1] = 1;
38: value[0] = 2.0;
39: value[1] = -1.0;
40: PetscCall(MatSetValues(mat, 1, &i, 2, col, value, INSERT_VALUES));
41: PetscCall(MatAssemblyBegin(mat, MAT_FINAL_ASSEMBLY));
42: PetscCall(MatAssemblyEnd(mat, MAT_FINAL_ASSEMBLY));
44: /* Create PC context and set up data structures */
45: PetscCall(PCCreate(PETSC_COMM_WORLD, &pc));
46: PetscCall(PCSetType(pc, PCSOR));
47: PetscCall(PCSetFromOptions(pc));
48: PetscCall(PCSetOperators(pc, mat, mat));
49: PetscCall(PCSetUp(pc));
51: value[0] = 1.0;
52: for (i = 0; i < n; i++) {
53: PetscCall(VecSet(u, 0.0));
54: PetscCall(VecSetValues(u, 1, &i, value, INSERT_VALUES));
55: PetscCall(VecAssemblyBegin(u));
56: PetscCall(VecAssemblyEnd(u));
57: PetscCall(PCApply(pc, u, b));
58: PetscCall(VecView(b, PETSC_VIEWER_STDOUT_SELF));
59: }
61: /* Free data structures */
62: PetscCall(MatDestroy(&mat));
63: PetscCall(PCDestroy(&pc));
64: PetscCall(VecDestroy(&u));
65: PetscCall(VecDestroy(&b));
66: PetscCall(PetscFinalize());
67: return 0;
68: }
70: /*TEST
72: test:
74: TEST*/