Actual source code: ex24.c
2: static char help[] = "Scatters from a parallel vector to a sequential vector.\n\
3: Tests where the local part of the scatter is a copy.\n\n";
5: #include <petscvec.h>
7: int main(int argc, char **argv)
8: {
9: PetscMPIInt size, rank;
10: PetscInt n = 5, i, *blks, bs = 1, m = 2;
11: PetscScalar value;
12: Vec x, y;
13: IS is1, is2;
14: VecScatter ctx = 0;
15: PetscViewer sviewer;
17: PetscFunctionBeginUser;
18: PetscCall(PetscInitialize(&argc, &argv, (char *)0, help));
20: PetscCall(PetscOptionsGetInt(NULL, NULL, "-n", &n, NULL));
21: PetscCall(PetscOptionsGetInt(NULL, NULL, "-bs", &bs, NULL));
23: PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
24: PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
26: /* create two vectors */
27: PetscCall(VecCreate(PETSC_COMM_WORLD, &x));
28: PetscCall(VecSetSizes(x, PETSC_DECIDE, size * bs * n));
29: PetscCall(VecSetFromOptions(x));
31: /* create two index sets */
32: if (rank < size - 1) m = n + 2;
33: else m = n;
35: PetscCall(PetscMalloc1(m, &blks));
36: blks[0] = n * rank;
37: for (i = 1; i < m; i++) blks[i] = blks[i - 1] + 1;
38: PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, m, blks, PETSC_COPY_VALUES, &is1));
39: PetscCall(PetscFree(blks));
41: PetscCall(VecCreateSeq(PETSC_COMM_SELF, bs * m, &y));
42: PetscCall(ISCreateStride(PETSC_COMM_SELF, bs * m, 0, 1, &is2));
44: /* each processor inserts the entire vector */
45: /* this is redundant but tests assembly */
46: for (i = 0; i < bs * n * size; i++) {
47: value = (PetscScalar)i;
48: PetscCall(VecSetValues(x, 1, &i, &value, INSERT_VALUES));
49: }
50: PetscCall(VecAssemblyBegin(x));
51: PetscCall(VecAssemblyEnd(x));
52: PetscCall(VecView(x, PETSC_VIEWER_STDOUT_WORLD));
54: PetscCall(VecScatterCreate(x, is1, y, is2, &ctx));
55: PetscCall(VecScatterBegin(ctx, x, y, INSERT_VALUES, SCATTER_FORWARD));
56: PetscCall(VecScatterEnd(ctx, x, y, INSERT_VALUES, SCATTER_FORWARD));
58: PetscCall(PetscViewerASCIIPushSynchronized(PETSC_VIEWER_STDOUT_WORLD));
59: PetscCall(PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_WORLD, "----\n"));
60: PetscCall(PetscViewerGetSubViewer(PETSC_VIEWER_STDOUT_WORLD, PETSC_COMM_SELF, &sviewer));
61: PetscCall(VecView(y, sviewer));
62: PetscCall(PetscFFlush(PETSC_STDOUT));
63: PetscCall(PetscViewerRestoreSubViewer(PETSC_VIEWER_STDOUT_WORLD, PETSC_COMM_SELF, &sviewer));
64: PetscCall(PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD));
65: PetscCall(PetscViewerASCIIPopSynchronized(PETSC_VIEWER_STDOUT_WORLD));
67: PetscCall(VecScatterDestroy(&ctx));
69: PetscCall(VecDestroy(&x));
70: PetscCall(VecDestroy(&y));
71: PetscCall(ISDestroy(&is1));
72: PetscCall(ISDestroy(&is2));
74: PetscCall(PetscFinalize());
75: return 0;
76: }
78: /*TEST
80: testset:
81: nsize: 3
82: output_file: output/ex24_1.out
83: filter: grep -v " type:"
84: test:
85: suffix: standard
86: args: -vec_type standard
87: test:
88: requires: cuda
89: suffix: cuda
90: args: -vec_type cuda
91: test:
92: requires: viennacl
93: suffix: viennacl
94: args: -vec_type viennacl
96: TEST*/