Actual source code: ex12.c
2: static char help[] = "Scatters from a sequential vector to a parallel vector.\n\
3: This does case when we are merely selecting the local part of the\n\
4: parallel vector.\n";
6: #include <petscvec.h>
8: int main(int argc, char **argv)
9: {
10: PetscMPIInt size, rank;
11: PetscInt n = 5, i;
12: PetscScalar value;
13: Vec x, y;
14: IS is1, is2;
15: VecScatter ctx = 0;
18: PetscInitialize(&argc, &argv, (char *)0, help);
20: MPI_Comm_size(PETSC_COMM_WORLD, &size);
21: MPI_Comm_rank(PETSC_COMM_WORLD, &rank);
23: /* create two vectors */
24: VecCreate(PETSC_COMM_WORLD, &x);
25: VecSetSizes(x, PETSC_DECIDE, size * n);
26: VecSetFromOptions(x);
27: VecCreateSeq(PETSC_COMM_SELF, n, &y);
29: /* create two index sets */
30: ISCreateStride(PETSC_COMM_SELF, n, n * rank, 1, &is1);
31: ISCreateStride(PETSC_COMM_SELF, n, 0, 1, &is2);
33: /* each processor inserts the entire vector */
34: /* this is redundant but tests assembly */
35: for (i = 0; i < n; i++) {
36: value = (PetscScalar)(i + 10 * rank);
37: VecSetValues(y, 1, &i, &value, INSERT_VALUES);
38: }
39: VecAssemblyBegin(y);
40: VecAssemblyEnd(y);
42: VecScatterCreate(y, is2, x, is1, &ctx);
43: VecScatterBegin(ctx, y, x, INSERT_VALUES, SCATTER_FORWARD);
44: VecScatterEnd(ctx, y, x, INSERT_VALUES, SCATTER_FORWARD);
45: VecScatterDestroy(&ctx);
47: VecView(x, PETSC_VIEWER_STDOUT_WORLD);
49: VecDestroy(&x);
50: VecDestroy(&y);
51: ISDestroy(&is1);
52: ISDestroy(&is2);
54: PetscFinalize();
55: return 0;
56: }
58: /*TEST
60: test:
61: nsize: 2
63: TEST*/