Actual source code: ex12.c
2: static char help[] = "Scatters from a parallel vector to a sequential vector. \n\
3: uses block index sets\n\n";
5: #include <petscvec.h>
7: int main(int argc, char **argv)
8: {
9: PetscInt bs = 1, n = 5, i, low;
10: PetscInt ix0[3] = {5, 7, 9}, iy0[3] = {1, 2, 4}, ix1[3] = {2, 3, 4}, iy1[3] = {0, 1, 3};
11: PetscMPIInt size, rank;
12: PetscScalar *array;
13: Vec x, y;
14: IS isx, isy;
15: VecScatter ctx;
17: PetscFunctionBeginUser;
18: PetscCall(PetscInitialize(&argc, &argv, (char *)0, help));
19: PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
20: PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
22: PetscCheck(size >= 2, PETSC_COMM_WORLD, PETSC_ERR_WRONG_MPI_SIZE, "Must run more than one processor");
24: PetscCall(PetscOptionsGetInt(NULL, NULL, "-bs", &bs, NULL));
25: n = bs * n;
27: /* Create vector x over shared memory */
28: PetscCall(VecCreate(PETSC_COMM_WORLD, &x));
29: PetscCall(VecSetSizes(x, n, PETSC_DECIDE));
30: PetscCall(VecSetFromOptions(x));
32: PetscCall(VecGetOwnershipRange(x, &low, NULL));
33: PetscCall(VecGetArray(x, &array));
34: for (i = 0; i < n; i++) array[i] = (PetscScalar)(i + low);
35: PetscCall(VecRestoreArray(x, &array));
37: /* Create a sequential vector y */
38: PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &y));
39: PetscCall(VecSet(y, 0.0));
41: /* Create two index sets */
42: if (rank == 0) {
43: PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 3, ix0, PETSC_COPY_VALUES, &isx));
44: PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 3, iy0, PETSC_COPY_VALUES, &isy));
45: } else {
46: PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 3, ix1, PETSC_COPY_VALUES, &isx));
47: PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 3, iy1, PETSC_COPY_VALUES, &isy));
48: }
50: if (rank == 10) {
51: PetscCall(PetscPrintf(PETSC_COMM_SELF, "\n[%d] isx:\n", rank));
52: PetscCall(ISView(isx, PETSC_VIEWER_STDOUT_SELF));
53: }
55: PetscCall(VecScatterCreate(x, isx, y, isy, &ctx));
56: PetscCall(VecScatterSetFromOptions(ctx));
58: /* Test forward vecscatter */
59: PetscCall(VecScatterBegin(ctx, x, y, ADD_VALUES, SCATTER_FORWARD));
60: PetscCall(VecScatterEnd(ctx, x, y, ADD_VALUES, SCATTER_FORWARD));
61: if (rank == 0) {
62: PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%d] y:\n", rank));
63: PetscCall(VecView(y, PETSC_VIEWER_STDOUT_SELF));
64: }
66: /* Test reverse vecscatter */
67: PetscCall(VecScale(y, -1.0));
68: if (rank) PetscCall(VecScale(y, 1.0 / (size - 1)));
70: PetscCall(VecScatterBegin(ctx, y, x, ADD_VALUES, SCATTER_REVERSE));
71: PetscCall(VecScatterEnd(ctx, y, x, ADD_VALUES, SCATTER_REVERSE));
72: PetscCall(VecView(x, PETSC_VIEWER_STDOUT_WORLD));
74: /* Free spaces */
75: PetscCall(VecScatterDestroy(&ctx));
76: PetscCall(ISDestroy(&isx));
77: PetscCall(ISDestroy(&isy));
78: PetscCall(VecDestroy(&x));
79: PetscCall(VecDestroy(&y));
80: PetscCall(PetscFinalize());
81: return 0;
82: }
84: /*TEST
86: test:
87: nsize: 3
89: TEST*/