xref: /petsc/src/mat/tests/ex87.c (revision a69119a591a03a9d906b29c0a4e9802e4d7c9795)
1 
2 static char help[] = "Tests MatCreateSubMatrices() for SBAIJ matrices\n\n";
3 
4 #include <petscmat.h>
5 
6 int main(int argc, char **args) {
7   Mat         BAIJ, SBAIJ, *subBAIJ, *subSBAIJ;
8   PetscViewer viewer;
9   char        file[PETSC_MAX_PATH_LEN];
10   PetscBool   flg;
11   PetscInt    n = 2, issize, M, N;
12   PetscMPIInt rank;
13   IS          isrow, iscol, irow[n], icol[n];
14 
15   PetscFunctionBeginUser;
16   PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
17   PetscCall(PetscOptionsGetString(NULL, NULL, "-f", file, sizeof(file), &flg));
18   PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD, file, FILE_MODE_READ, &viewer));
19 
20   PetscCall(MatCreate(PETSC_COMM_WORLD, &BAIJ));
21   PetscCall(MatSetType(BAIJ, MATMPIBAIJ));
22   PetscCall(MatLoad(BAIJ, viewer));
23   PetscCall(PetscViewerDestroy(&viewer));
24 
25   PetscCall(PetscViewerBinaryOpen(PETSC_COMM_WORLD, file, FILE_MODE_READ, &viewer));
26   PetscCall(MatCreate(PETSC_COMM_WORLD, &SBAIJ));
27   PetscCall(MatSetType(SBAIJ, MATMPISBAIJ));
28   PetscCall(MatLoad(SBAIJ, viewer));
29   PetscCall(PetscViewerDestroy(&viewer));
30 
31   PetscCall(MatGetSize(BAIJ, &M, &N));
32   issize = M / 4;
33   PetscCall(ISCreateStride(PETSC_COMM_SELF, issize, 0, 1, &isrow));
34   irow[0] = irow[1] = isrow;
35   issize            = N / 2;
36   PetscCall(ISCreateStride(PETSC_COMM_SELF, issize, 0, 1, &iscol));
37   icol[0] = icol[1] = iscol;
38   PetscCall(MatCreateSubMatrices(BAIJ, n, irow, icol, MAT_INITIAL_MATRIX, &subBAIJ));
39   PetscCall(MatCreateSubMatrices(BAIJ, n, irow, icol, MAT_REUSE_MATRIX, &subBAIJ));
40 
41   /* irow and icol must be same for SBAIJ matrices! */
42   icol[0] = icol[1] = isrow;
43   PetscCall(MatCreateSubMatrices(SBAIJ, n, irow, icol, MAT_INITIAL_MATRIX, &subSBAIJ));
44   PetscCall(MatCreateSubMatrices(SBAIJ, n, irow, icol, MAT_REUSE_MATRIX, &subSBAIJ));
45 
46   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
47   if (rank == 0) {
48     PetscCall(MatView(subBAIJ[0], PETSC_VIEWER_STDOUT_SELF));
49     PetscCall(MatView(subSBAIJ[0], PETSC_VIEWER_STDOUT_SELF));
50   }
51 
52   /* Free data structures */
53   PetscCall(ISDestroy(&isrow));
54   PetscCall(ISDestroy(&iscol));
55   PetscCall(MatDestroySubMatrices(n, &subBAIJ));
56   PetscCall(MatDestroySubMatrices(n, &subSBAIJ));
57   PetscCall(MatDestroy(&BAIJ));
58   PetscCall(MatDestroy(&SBAIJ));
59 
60   PetscCall(PetscFinalize());
61   return 0;
62 }
63