1 static char help[] = "Tests automatic allocation of matrix storage space.\n\n";
2
3 #include <petscmat.h>
4
main(int argc,char ** args)5 int main(int argc, char **args)
6 {
7 Mat C;
8 PetscInt i, j, m = 3, n = 3, Ii, J;
9 PetscScalar v;
10 MatInfo info;
11
12 PetscFunctionBeginUser;
13 PetscCall(PetscInitialize(&argc, &args, NULL, help));
14 PetscCall(PetscOptionsGetInt(NULL, NULL, "-m", &m, NULL));
15 PetscCall(PetscOptionsGetInt(NULL, NULL, "-n", &n, NULL));
16
17 /* create the matrix for the five point stencil, YET AGAIN */
18 PetscCall(MatCreate(PETSC_COMM_SELF, &C));
19 PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n));
20 PetscCall(MatSetFromOptions(C));
21 PetscCall(MatSetUp(C));
22 for (i = 0; i < m; i++) {
23 for (j = 0; j < n; j++) {
24 v = -1.0;
25 Ii = j + n * i;
26 if (i > 0) {
27 J = Ii - n;
28 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
29 }
30 if (i < m - 1) {
31 J = Ii + n;
32 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
33 }
34 if (j > 0) {
35 J = Ii - 1;
36 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
37 }
38 if (j < n - 1) {
39 J = Ii + 1;
40 PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
41 }
42 v = 4.0;
43 PetscCall(MatSetValues(C, 1, &Ii, 1, &Ii, &v, INSERT_VALUES));
44 }
45 }
46 PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
47 PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
48 PetscCall(MatView(C, PETSC_VIEWER_STDOUT_SELF));
49
50 PetscCall(MatGetInfo(C, MAT_LOCAL, &info));
51 PetscCall(PetscPrintf(PETSC_COMM_SELF, "matrix nonzeros = %" PetscInt_FMT ", allocated nonzeros = %" PetscInt_FMT "\n", (PetscInt)info.nz_used, (PetscInt)info.nz_allocated));
52
53 PetscCall(MatDestroy(&C));
54 PetscCall(PetscFinalize());
55 return 0;
56 }
57
58 /*TEST
59
60 test:
61
62 TEST*/
63