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;
15: PetscInitialize(&argc, &args, (char *)0, help);
16: MPI_Comm_rank(PETSC_COMM_WORLD, &rank);
17: MPI_Comm_size(PETSC_COMM_WORLD, &size);
18: n = 2 * size;
20: MatCreate(PETSC_COMM_WORLD, &C);
21: MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n);
22: MatSetFromOptions(C);
23: 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: 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: MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES);
34: }
35: }
36: MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY);
37: MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY);
38: PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_COMMON);
39: MatView(C, PETSC_VIEWER_STDOUT_WORLD);
40: PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
42: /*
43: Generate a new matrix consisting every column of the original matrix
44: */
45: MatGetOwnershipRange(C, &rstart, &rend);
46: MatGetOwnershipRangeColumn(C, &cstart, &cend);
48: ISCreateStride(PETSC_COMM_WORLD, rend - rstart > 0 ? rend - rstart - 1 : 0, rstart, 1, &isrow);
49: ISCreateStride(PETSC_COMM_WORLD, cend - cstart, cstart, 1, &iscol);
50: 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: MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES);
58: }
59: MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY);
60: MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY);
62: MatCreateSubMatrix(C, isrow, NULL, MAT_REUSE_MATRIX, &A);
63: PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_COMMON);
64: MatView(A, PETSC_VIEWER_STDOUT_WORLD);
65: PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD);
67: ISDestroy(&isrow);
68: ISDestroy(&iscol);
69: MatDestroy(&A);
70: MatDestroy(&C);
71: PetscFinalize();
72: return 0;
73: }
75: /*TEST
77: test:
78: nsize: 2
80: TEST*/