Actual source code: ex194.c
1: static char help[] = "Tests MatCreateSubmatrix() with certain entire rows of matrix, modified from ex181.c.";
3: #include <petscmat.h>
5: int main(int argc, char **args)
6: {
7: Mat C, A;
8: PetscInt i, j, m = 3, n = 2, rstart, rend, cstart, cend;
9: PetscMPIInt size, rank;
10: PetscScalar v;
11: IS isrow, iscol;
13: PetscFunctionBeginUser;
14: PetscCall(PetscInitialize(&argc, &args, NULL, help));
15: PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
16: PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
17: n = 2 * size;
19: PetscCall(MatCreate(PETSC_COMM_WORLD, &C));
20: PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n));
21: PetscCall(MatSetFromOptions(C));
22: PetscCall(MatSetUp(C));
24: /*
25: This is JUST to generate a nice test matrix, all processors fill up
26: the entire matrix. This is not something one would ever do in practice.
27: */
28: PetscCall(MatGetOwnershipRange(C, &rstart, &rend));
29: for (i = rstart; i < rend; i++) {
30: for (j = 0; j < m * n; j++) {
31: v = i + j + 1;
32: PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES));
33: }
34: }
35: PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
36: PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
37: PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_COMMON));
38: PetscCall(MatView(C, PETSC_VIEWER_STDOUT_WORLD));
39: PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
41: /*
42: Generate a new matrix consisting every column of the original matrix
43: */
44: PetscCall(MatGetOwnershipRange(C, &rstart, &rend));
45: PetscCall(MatGetOwnershipRangeColumn(C, &cstart, &cend));
47: PetscCall(ISCreateStride(PETSC_COMM_WORLD, rend - rstart > 0 ? rend - rstart - 1 : 0, rstart, 1, &isrow));
48: PetscCall(ISCreateStride(PETSC_COMM_WORLD, cend - cstart, cstart, 1, &iscol));
49: PetscCall(MatCreateSubMatrix(C, isrow, NULL, MAT_INITIAL_MATRIX, &A));
51: /* Change C to test the case MAT_REUSE_MATRIX */
52: if (rank == 0) {
53: i = 0;
54: j = 0;
55: v = 100;
56: PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES));
57: }
58: PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
59: PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
61: PetscCall(MatCreateSubMatrix(C, isrow, NULL, MAT_REUSE_MATRIX, &A));
62: PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_COMMON));
63: PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));
64: PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
66: PetscCall(ISDestroy(&isrow));
67: PetscCall(ISDestroy(&iscol));
68: PetscCall(MatDestroy(&A));
69: PetscCall(MatDestroy(&C));
70: PetscCall(PetscFinalize());
71: return 0;
72: }
74: /*TEST
76: test:
77: nsize: 2
79: TEST*/