Actual source code: ex194.c
2: static char help[] = "Tests MatCreateSubmatrix() with certain entire rows of matrix, modified from ex181.c.";
4: #include <petscmat.h>
6: int main(int argc, char **args)
7: {
8: Mat C, A;
9: PetscInt i, j, m = 3, n = 2, rstart, rend, cstart, cend;
10: PetscMPIInt size, rank;
11: PetscScalar v;
12: IS isrow, iscol;
14: PetscFunctionBeginUser;
15: PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
16: PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
17: PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
18: n = 2 * size;
20: PetscCall(MatCreate(PETSC_COMM_WORLD, &C));
21: PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n));
22: PetscCall(MatSetFromOptions(C));
23: PetscCall(MatSetUp(C));
25: /*
26: This is JUST to generate a nice test matrix, all processors fill up
27: the entire matrix. This is not something one would ever do in practice.
28: */
29: PetscCall(MatGetOwnershipRange(C, &rstart, &rend));
30: for (i = rstart; i < rend; i++) {
31: for (j = 0; j < m * n; j++) {
32: v = i + j + 1;
33: PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES));
34: }
35: }
36: PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
37: PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
38: PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_COMMON));
39: PetscCall(MatView(C, PETSC_VIEWER_STDOUT_WORLD));
40: PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
42: /*
43: Generate a new matrix consisting every column of the original matrix
44: */
45: PetscCall(MatGetOwnershipRange(C, &rstart, &rend));
46: PetscCall(MatGetOwnershipRangeColumn(C, &cstart, &cend));
48: PetscCall(ISCreateStride(PETSC_COMM_WORLD, rend - rstart > 0 ? rend - rstart - 1 : 0, rstart, 1, &isrow));
49: PetscCall(ISCreateStride(PETSC_COMM_WORLD, cend - cstart, cstart, 1, &iscol));
50: PetscCall(MatCreateSubMatrix(C, isrow, NULL, MAT_INITIAL_MATRIX, &A));
52: /* Change C to test the case MAT_REUSE_MATRIX */
53: if (rank == 0) {
54: i = 0;
55: j = 0;
56: v = 100;
57: PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES));
58: }
59: PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
60: PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
62: PetscCall(MatCreateSubMatrix(C, isrow, NULL, MAT_REUSE_MATRIX, &A));
63: PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_COMMON));
64: PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));
65: PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
67: PetscCall(ISDestroy(&isrow));
68: PetscCall(ISDestroy(&iscol));
69: PetscCall(MatDestroy(&A));
70: PetscCall(MatDestroy(&C));
71: PetscCall(PetscFinalize());
72: return 0;
73: }
75: /*TEST
77: test:
78: nsize: 2
80: TEST*/