xref: /petsc/src/mat/tests/ex181.c (revision d5b43468fb8780a8feea140ccd6fa3e6a50411cc)
1 
2 static char help[] = "Tests MatCreateSubmatrix() with entire matrix, modified from ex59.c.";
3 
4 #include <petscmat.h>
5 
6 int main(int argc, char **args)
7 {
8   Mat         C, A, Adup;
9   PetscInt    i, j, m = 3, n = 2, rstart, rend;
10   PetscMPIInt size, rank;
11   PetscScalar v;
12   IS          isrow;
13   PetscBool   detect_bug = PETSC_FALSE;
14 
15   PetscFunctionBeginUser;
16   PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
17   PetscCall(PetscOptionsHasName(NULL, NULL, "-detect_bug", &detect_bug));
18   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
19   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
20   n = 2 * size;
21 
22   PetscCall(MatCreate(PETSC_COMM_WORLD, &C));
23   PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n));
24   PetscCall(MatSetFromOptions(C));
25   PetscCall(MatSetUp(C));
26 
27   /*
28         This is JUST to generate a nice test matrix, all processors fill up
29     the entire matrix. This is not something one would ever do in practice.
30   */
31   PetscCall(MatGetOwnershipRange(C, &rstart, &rend));
32   for (i = rstart; i < rend; i++) {
33     for (j = 0; j < m * n; j++) {
34       v = i + j + 1;
35       PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES));
36     }
37   }
38   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
39   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
40   PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_COMMON));
41   PetscCall(MatView(C, PETSC_VIEWER_STDOUT_WORLD));
42   PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
43 
44   /*
45      Generate a new matrix consisting every row and column of the original matrix
46   */
47   PetscCall(MatGetOwnershipRange(C, &rstart, &rend));
48 
49   /* Create parallel IS with the rows we want on THIS processor */
50   if (detect_bug && rank == 0) {
51     PetscCall(ISCreateStride(PETSC_COMM_WORLD, 1, rstart, 1, &isrow));
52   } else {
53     PetscCall(ISCreateStride(PETSC_COMM_WORLD, rend - rstart, rstart, 1, &isrow));
54   }
55   PetscCall(MatCreateSubMatrix(C, isrow, NULL, MAT_INITIAL_MATRIX, &A));
56 
57   /* Change C to test the case MAT_REUSE_MATRIX */
58   if (rank == 0) {
59     i = 0;
60     j = 0;
61     v = 100;
62     PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES));
63   }
64   PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
65   PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
66 
67   PetscCall(MatCreateSubMatrix(C, isrow, NULL, MAT_REUSE_MATRIX, &A));
68   PetscCall(PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD, PETSC_VIEWER_ASCII_COMMON));
69   PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));
70   PetscCall(PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD));
71 
72   /* Test MatDuplicate */
73   PetscCall(MatDuplicate(A, MAT_COPY_VALUES, &Adup));
74   PetscCall(MatDestroy(&Adup));
75 
76   PetscCall(ISDestroy(&isrow));
77   PetscCall(MatDestroy(&A));
78   PetscCall(MatDestroy(&C));
79   PetscCall(PetscFinalize());
80   return 0;
81 }
82 
83 /*TEST
84 
85    test:
86       nsize: 2
87       filter: grep -v "Mat Object"
88       requires: !complex
89 
90    test:
91       suffix: 2
92       nsize: 3
93       args: -detect_bug
94       filter: grep -v "Mat Object"
95       requires: !complex
96 
97 TEST*/
98