Actual source code: ex3.c
2: static char help[] = "Tests relaxation for dense matrices.\n\n";
4: #include <petscmat.h>
6: int main(int argc, char **args)
7: {
8: Mat C;
9: Vec u, x, b, e;
10: PetscInt i, n = 10, midx[3];
11: PetscScalar v[3];
12: PetscReal omega = 1.0, norm;
14: PetscFunctionBeginUser;
15: PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
16: PetscCall(PetscOptionsGetReal(NULL, NULL, "-omega", &omega, NULL));
17: PetscCall(PetscOptionsGetInt(NULL, NULL, "-n", &n, NULL));
19: PetscCall(MatCreate(PETSC_COMM_SELF, &C));
20: PetscCall(MatSetSizes(C, n, n, n, n));
21: PetscCall(MatSetType(C, MATSEQDENSE));
22: PetscCall(MatSetUp(C));
23: PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &b));
24: PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &x));
25: PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &u));
26: PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &e));
27: PetscCall(VecSet(u, 1.0));
28: PetscCall(VecSet(x, 0.0));
30: v[0] = -1.;
31: v[1] = 2.;
32: v[2] = -1.;
33: for (i = 1; i < n - 1; i++) {
34: midx[0] = i - 1;
35: midx[1] = i;
36: midx[2] = i + 1;
37: PetscCall(MatSetValues(C, 1, &i, 3, midx, v, INSERT_VALUES));
38: }
39: i = 0;
40: midx[0] = 0;
41: midx[1] = 1;
42: v[0] = 2.0;
43: v[1] = -1.;
44: PetscCall(MatSetValues(C, 1, &i, 2, midx, v, INSERT_VALUES));
45: i = n - 1;
46: midx[0] = n - 2;
47: midx[1] = n - 1;
48: v[0] = -1.0;
49: v[1] = 2.;
50: PetscCall(MatSetValues(C, 1, &i, 2, midx, v, INSERT_VALUES));
52: PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
53: PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
55: PetscCall(MatMult(C, u, b));
57: for (i = 0; i < n; i++) {
58: PetscCall(MatSOR(C, b, omega, SOR_FORWARD_SWEEP, 0.0, 1, 1, x));
59: PetscCall(VecWAXPY(e, -1.0, x, u));
60: PetscCall(VecNorm(e, NORM_2, &norm));
61: PetscCall(PetscPrintf(PETSC_COMM_SELF, "2-norm of error %g\n", (double)norm));
62: }
63: PetscCall(MatDestroy(&C));
64: PetscCall(VecDestroy(&x));
65: PetscCall(VecDestroy(&b));
66: PetscCall(VecDestroy(&u));
67: PetscCall(VecDestroy(&e));
68: PetscCall(PetscFinalize());
69: return 0;
70: }
72: /*TEST
74: test:
76: TEST*/