1 static char help[] = "Tests MatCreateSubmatrix() with certain entire rows of matrix, modified from ex181.c.";
2
3 #include <petscmat.h>
4
main(int argc,char ** args)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;
12
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;
18
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));
23
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));
40
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));
46
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));
50
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));
60
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));
65
66 PetscCall(ISDestroy(&isrow));
67 PetscCall(ISDestroy(&iscol));
68 PetscCall(MatDestroy(&A));
69 PetscCall(MatDestroy(&C));
70 PetscCall(PetscFinalize());
71 return 0;
72 }
73
74 /*TEST
75
76 test:
77 nsize: 2
78
79 TEST*/
80