1 static char help[] = "Tests reordering a matrix.\n\n";
2
3 #include <petscmat.h>
4
main(int argc,char ** args)5 int main(int argc, char **args)
6 {
7 Mat C;
8 PetscInt i, j, m = 5, n = 5, Ii, J;
9 PetscScalar v;
10 IS perm, iperm;
11
12 PetscFunctionBeginUser;
13 PetscCall(PetscInitialize(&argc, &args, NULL, help));
14 PetscCall(MatCreate(PETSC_COMM_SELF, &C));
15 PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n));
16 PetscCall(MatSetFromOptions(C));
17 PetscCall(MatSetUp(C));
18
19 /* create the matrix for the five point stencil, YET AGAIN*/
20 for (i = 0; i < m; i++) {
21 for (j = 0; j < n; j++) {
22 v = -1.0;
23 Ii = j + n * i;
24 if (i > 0) {
25 J = Ii - n;
26 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
27 }
28 if (i < m - 1) {
29 J = Ii + n;
30 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
31 }
32 if (j > 0) {
33 J = Ii - 1;
34 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
35 }
36 if (j < n - 1) {
37 J = Ii + 1;
38 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
39 }
40 v = 4.0;
41 PetscCall(MatSetValues(C, 1, &Ii, 1, &Ii, &v, INSERT_VALUES));
42 }
43 }
44 PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
45 PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
46
47 PetscCall(MatGetOrdering(C, MATORDERINGND, &perm, &iperm));
48 PetscCall(ISView(perm, PETSC_VIEWER_STDOUT_SELF));
49 PetscCall(ISView(iperm, PETSC_VIEWER_STDOUT_SELF));
50 PetscCall(MatView(C, PETSC_VIEWER_STDOUT_SELF));
51
52 PetscCall(ISDestroy(&perm));
53 PetscCall(ISDestroy(&iperm));
54 PetscCall(MatDestroy(&C));
55 PetscCall(PetscFinalize());
56 return 0;
57 }
58
59 /*TEST
60
61 test:
62
63 TEST*/
64