Actual source code: ex4.c
2: static char help[] = "Demonstrates the use of fast Richardson for SOR. And tests\n\
3: the MatSOR() routines.\n\n";
5: #include <petscpc.h>
7: int main(int argc, char **args)
8: {
9: Mat mat;
10: Vec b, u;
11: PC pc;
12: PetscInt n = 5, i, col[3];
13: PetscScalar value[3];
15: PetscFunctionBeginUser;
16: PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
17: /* Create vectors */
18: PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &b));
19: PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &u));
21: /* Create and assemble matrix */
22: PetscCall(MatCreateSeqDense(PETSC_COMM_SELF, n, n, NULL, &mat));
23: value[0] = -1.0;
24: value[1] = 2.0;
25: value[2] = -1.0;
26: for (i = 1; i < n - 1; i++) {
27: col[0] = i - 1;
28: col[1] = i;
29: col[2] = i + 1;
30: PetscCall(MatSetValues(mat, 1, &i, 3, col, value, INSERT_VALUES));
31: }
32: i = n - 1;
33: col[0] = n - 2;
34: col[1] = n - 1;
35: PetscCall(MatSetValues(mat, 1, &i, 2, col, value, INSERT_VALUES));
36: i = 0;
37: col[0] = 0;
38: col[1] = 1;
39: value[0] = 2.0;
40: value[1] = -1.0;
41: PetscCall(MatSetValues(mat, 1, &i, 2, col, value, INSERT_VALUES));
42: PetscCall(MatAssemblyBegin(mat, MAT_FINAL_ASSEMBLY));
43: PetscCall(MatAssemblyEnd(mat, MAT_FINAL_ASSEMBLY));
45: /* Create PC context and set up data structures */
46: PetscCall(PCCreate(PETSC_COMM_WORLD, &pc));
47: PetscCall(PCSetType(pc, PCSOR));
48: PetscCall(PCSetFromOptions(pc));
49: PetscCall(PCSetOperators(pc, mat, mat));
50: PetscCall(PCSetUp(pc));
52: value[0] = 1.0;
53: for (i = 0; i < n; i++) {
54: PetscCall(VecSet(u, 0.0));
55: PetscCall(VecSetValues(u, 1, &i, value, INSERT_VALUES));
56: PetscCall(VecAssemblyBegin(u));
57: PetscCall(VecAssemblyEnd(u));
58: PetscCall(PCApply(pc, u, b));
59: PetscCall(VecView(b, PETSC_VIEWER_STDOUT_SELF));
60: }
62: /* Free data structures */
63: PetscCall(MatDestroy(&mat));
64: PetscCall(PCDestroy(&pc));
65: PetscCall(VecDestroy(&u));
66: PetscCall(VecDestroy(&b));
67: PetscCall(PetscFinalize());
68: return 0;
69: }
71: /*TEST
73: test:
75: TEST*/