1 static char help[] = "Tests MatCreateSubMatrices().\n\n";
2
3 #include <petscmat.h>
4
main(int argc,char ** args)5 int main(int argc, char **args)
6 {
7 Mat A, B, *Bsub;
8 PetscInt i, j, m = 6, n = 6, N = 36, Ii, J;
9 PetscScalar v;
10 IS isrow;
11
12 PetscFunctionBeginUser;
13 PetscCall(PetscInitialize(&argc, &args, NULL, help));
14 PetscCall(MatCreateSeqAIJ(PETSC_COMM_WORLD, N, N, 5, NULL, &A));
15 for (i = 0; i < m; i++) {
16 for (j = 0; j < n; j++) {
17 v = -1.0;
18 Ii = j + n * i;
19 if (i > 0) {
20 J = Ii - n;
21 PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
22 }
23 if (i < m - 1) {
24 J = Ii + n;
25 PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
26 }
27 if (j > 0) {
28 J = Ii - 1;
29 PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
30 }
31 if (j < n - 1) {
32 J = Ii + 1;
33 PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
34 }
35 v = 4.0;
36 PetscCall(MatSetValues(A, 1, &Ii, 1, &Ii, &v, INSERT_VALUES));
37 }
38 }
39 PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
40 PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
41 PetscCall(MatView(A, PETSC_VIEWER_STDOUT_SELF));
42
43 /* take the first diagonal block */
44 PetscCall(ISCreateStride(PETSC_COMM_WORLD, m, 0, 1, &isrow));
45 PetscCall(MatCreateSubMatrices(A, 1, &isrow, &isrow, MAT_INITIAL_MATRIX, &Bsub));
46 B = *Bsub;
47 PetscCall(ISDestroy(&isrow));
48 PetscCall(MatView(B, PETSC_VIEWER_STDOUT_SELF));
49 PetscCall(MatDestroySubMatrices(1, &Bsub));
50
51 /* take a strided block */
52 PetscCall(ISCreateStride(PETSC_COMM_WORLD, m, 0, 2, &isrow));
53 PetscCall(MatCreateSubMatrices(A, 1, &isrow, &isrow, MAT_INITIAL_MATRIX, &Bsub));
54 B = *Bsub;
55 PetscCall(ISDestroy(&isrow));
56 PetscCall(MatView(B, PETSC_VIEWER_STDOUT_SELF));
57 PetscCall(MatDestroySubMatrices(1, &Bsub));
58
59 /* take the last block */
60 PetscCall(ISCreateStride(PETSC_COMM_WORLD, m, N - m - 1, 1, &isrow));
61 PetscCall(MatCreateSubMatrices(A, 1, &isrow, &isrow, MAT_INITIAL_MATRIX, &Bsub));
62 B = *Bsub;
63 PetscCall(ISDestroy(&isrow));
64 PetscCall(MatView(B, PETSC_VIEWER_STDOUT_SELF));
65
66 PetscCall(MatDestroySubMatrices(1, &Bsub));
67 PetscCall(MatDestroy(&A));
68
69 PetscCall(PetscFinalize());
70 return 0;
71 }
72
73 /*TEST
74
75 test:
76
77 TEST*/
78