Actual source code: ex14.c
1: static char help[] = "Tests sequential and parallel MatGetRow() and MatRestoreRow().\n";
3: #include <petscmat.h>
5: int main(int argc, char **args)
6: {
7: Mat C;
8: PetscInt i, j, m = 5, n = 5, Ii, J, nz, rstart, rend;
9: PetscMPIInt rank;
10: const PetscInt *idx;
11: PetscScalar v;
12: const PetscScalar *values;
14: PetscFunctionBeginUser;
15: PetscCall(PetscInitialize(&argc, &args, NULL, help));
16: /* Create the matrix for the five point stencil, YET AGAIN */
17: PetscCall(MatCreate(PETSC_COMM_WORLD, &C));
18: PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n));
19: PetscCall(MatSetFromOptions(C));
20: PetscCall(MatSetUp(C));
21: for (i = 0; i < m; i++) {
22: for (j = 0; j < n; j++) {
23: v = -1.0;
24: Ii = j + n * i;
25: if (i > 0) {
26: J = Ii - n;
27: PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
28: }
29: if (i < m - 1) {
30: J = Ii + n;
31: PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
32: }
33: if (j > 0) {
34: J = Ii - 1;
35: PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
36: }
37: if (j < n - 1) {
38: J = Ii + 1;
39: PetscCall(MatSetValues(C, 1, &Ii, 1, &J, &v, INSERT_VALUES));
40: }
41: v = 4.0;
42: PetscCall(MatSetValues(C, 1, &Ii, 1, &Ii, &v, INSERT_VALUES));
43: }
44: }
45: PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
46: PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));
47: PetscCall(MatView(C, PETSC_VIEWER_STDOUT_WORLD));
49: PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
50: PetscCall(MatGetOwnershipRange(C, &rstart, &rend));
51: for (i = rstart; i < rend; i++) {
52: PetscCall(MatGetRow(C, i, &nz, &idx, &values));
53: if (rank == 0) {
54: for (j = 0; j < nz; j++) PetscCall(PetscPrintf(PETSC_COMM_SELF, "%" PetscInt_FMT " %g ", idx[j], (double)PetscRealPart(values[j])));
55: PetscCall(PetscPrintf(PETSC_COMM_SELF, "\n"));
56: }
57: PetscCall(MatRestoreRow(C, i, &nz, &idx, &values));
58: }
60: PetscCall(MatDestroy(&C));
61: PetscCall(PetscFinalize());
62: return 0;
63: }
65: /*TEST
67: test:
69: TEST*/