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;
15: PetscInitialize(&argc, &args, (char *)0, help);
16: PetscOptionsGetReal(NULL, NULL, "-omega", &omega, NULL);
17: PetscOptionsGetInt(NULL, NULL, "-n", &n, NULL);
19: MatCreate(PETSC_COMM_SELF, &C);
20: MatSetSizes(C, n, n, n, n);
21: MatSetType(C, MATSEQDENSE);
22: MatSetUp(C);
23: VecCreateSeq(PETSC_COMM_SELF, n, &b);
24: VecCreateSeq(PETSC_COMM_SELF, n, &x);
25: VecCreateSeq(PETSC_COMM_SELF, n, &u);
26: VecCreateSeq(PETSC_COMM_SELF, n, &e);
27: VecSet(u, 1.0);
28: 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: 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: 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: MatSetValues(C, 1, &i, 2, midx, v, INSERT_VALUES);
52: MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY);
53: MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY);
55: MatMult(C, u, b);
57: for (i = 0; i < n; i++) {
58: MatSOR(C, b, omega, SOR_FORWARD_SWEEP, 0.0, 1, 1, x);
59: VecWAXPY(e, -1.0, x, u);
60: VecNorm(e, NORM_2, &norm);
61: PetscPrintf(PETSC_COMM_SELF, "2-norm of error %g\n", (double)norm);
62: }
63: MatDestroy(&C);
64: VecDestroy(&x);
65: VecDestroy(&b);
66: VecDestroy(&u);
67: VecDestroy(&e);
68: PetscFinalize();
69: return 0;
70: }
72: /*TEST
74: test:
76: TEST*/