1 static char help[] = "Scatters from a parallel vector to a sequential vector. \n\
2 uses block index sets\n\n";
3
4 #include <petscvec.h>
5
main(int argc,char ** argv)6 int main(int argc, char **argv)
7 {
8 PetscInt bs = 1, n = 5, i, low;
9 PetscInt ix0[3] = {5, 7, 9}, iy0[3] = {1, 2, 4}, ix1[3] = {2, 3, 4}, iy1[3] = {0, 1, 3};
10 PetscMPIInt size, rank;
11 PetscScalar *array;
12 Vec x, y;
13 IS isx, isy;
14 VecScatter ctx;
15
16 PetscFunctionBeginUser;
17 PetscCall(PetscInitialize(&argc, &argv, NULL, help));
18 PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
19 PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
20
21 PetscCheck(size >= 2, PETSC_COMM_WORLD, PETSC_ERR_WRONG_MPI_SIZE, "Must run more than one processor");
22
23 PetscCall(PetscOptionsGetInt(NULL, NULL, "-bs", &bs, NULL));
24 n = bs * n;
25
26 /* Create vector x over shared memory */
27 PetscCall(VecCreate(PETSC_COMM_WORLD, &x));
28 PetscCall(VecSetSizes(x, n, PETSC_DECIDE));
29 PetscCall(VecSetFromOptions(x));
30
31 PetscCall(VecGetOwnershipRange(x, &low, NULL));
32 PetscCall(VecGetArray(x, &array));
33 for (i = 0; i < n; i++) array[i] = (PetscScalar)(i + low);
34 PetscCall(VecRestoreArray(x, &array));
35
36 /* Create a sequential vector y */
37 PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &y));
38 PetscCall(VecSet(y, 0.0));
39
40 /* Create two index sets */
41 if (rank == 0) {
42 PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 3, ix0, PETSC_COPY_VALUES, &isx));
43 PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 3, iy0, PETSC_COPY_VALUES, &isy));
44 } else {
45 PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 3, ix1, PETSC_COPY_VALUES, &isx));
46 PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 3, iy1, PETSC_COPY_VALUES, &isy));
47 }
48
49 if (rank == 10) {
50 PetscCall(PetscPrintf(PETSC_COMM_SELF, "\n[%d] isx:\n", rank));
51 PetscCall(ISView(isx, PETSC_VIEWER_STDOUT_SELF));
52 }
53
54 PetscCall(VecScatterCreate(x, isx, y, isy, &ctx));
55 PetscCall(VecScatterSetFromOptions(ctx));
56
57 /* Test forward vecscatter */
58 PetscCall(VecScatterBegin(ctx, x, y, ADD_VALUES, SCATTER_FORWARD));
59 PetscCall(VecScatterEnd(ctx, x, y, ADD_VALUES, SCATTER_FORWARD));
60 if (rank == 0) {
61 PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%d] y:\n", rank));
62 PetscCall(VecView(y, PETSC_VIEWER_STDOUT_SELF));
63 }
64
65 /* Test reverse vecscatter */
66 PetscCall(VecScale(y, -1.0));
67 if (rank) PetscCall(VecScale(y, 1.0 / (size - 1)));
68
69 PetscCall(VecScatterBegin(ctx, y, x, ADD_VALUES, SCATTER_REVERSE));
70 PetscCall(VecScatterEnd(ctx, y, x, ADD_VALUES, SCATTER_REVERSE));
71 PetscCall(VecView(x, PETSC_VIEWER_STDOUT_WORLD));
72
73 /* Free spaces */
74 PetscCall(VecScatterDestroy(&ctx));
75 PetscCall(ISDestroy(&isx));
76 PetscCall(ISDestroy(&isy));
77 PetscCall(VecDestroy(&x));
78 PetscCall(VecDestroy(&y));
79 PetscCall(PetscFinalize());
80 return 0;
81 }
82
83 /*TEST
84
85 test:
86 nsize: 3
87
88 TEST*/
89