1 2 static char help[] = "Scatters from a parallel vector to a sequential vector. \n\ 3 uses block index sets\n\n"; 4 5 #include <petscvec.h> 6 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; 16 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)); 21 22 PetscCheck(size >= 2, PETSC_COMM_WORLD, PETSC_ERR_WRONG_MPI_SIZE, "Must run more than one processor"); 23 24 PetscCall(PetscOptionsGetInt(NULL, NULL, "-bs", &bs, NULL)); 25 n = bs * n; 26 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)); 31 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)); 36 37 /* Create a sequential vector y */ 38 PetscCall(VecCreateSeq(PETSC_COMM_SELF, n, &y)); 39 PetscCall(VecSet(y, 0.0)); 40 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 } 49 50 if (rank == 10) { 51 PetscCall(PetscPrintf(PETSC_COMM_SELF, "\n[%d] isx:\n", rank)); 52 PetscCall(ISView(isx, PETSC_VIEWER_STDOUT_SELF)); 53 } 54 55 PetscCall(VecScatterCreate(x, isx, y, isy, &ctx)); 56 PetscCall(VecScatterSetFromOptions(ctx)); 57 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 } 65 66 /* Test reverse vecscatter */ 67 PetscCall(VecScale(y, -1.0)); 68 if (rank) PetscCall(VecScale(y, 1.0 / (size - 1))); 69 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)); 73 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 } 83 84 /*TEST 85 86 test: 87 nsize: 3 88 89 TEST*/ 90