Actual source code: ex11.c

  1: static char help[] = "Scatters between parallel vectors. \n\
  2: uses block index sets\n\n";

  4: #include <petscvec.h>

  6: int main(int argc, char **argv)
  7: {
  8:   PetscInt       bs = 1, n = 5, N, i, low;
  9:   PetscInt       ix0[3] = {5, 7, 9}, iy0[3] = {1, 2, 4}, ix1[3] = {2, 3, 1}, iy1[3] = {0, 3, 9};
 10:   PetscMPIInt    size, rank;
 11:   PetscScalar   *array;
 12:   Vec            x, x1, y;
 13:   IS             isx, isy;
 14:   VecScatter     ctx;
 15:   VecScatterType type;
 16:   PetscBool      flg;

 18:   PetscFunctionBeginUser;
 19:   PetscCall(PetscInitialize(&argc, &argv, NULL, help));
 20:   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
 21:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));

 23:   PetscCheck(size >= 2, PETSC_COMM_WORLD, PETSC_ERR_WRONG_MPI_SIZE, "Must run more than one processor");

 25:   PetscCall(PetscOptionsGetInt(NULL, NULL, "-bs", &bs, NULL));
 26:   n = bs * n;

 28:   /* Create vector x over shared memory */
 29:   PetscCall(VecCreate(PETSC_COMM_WORLD, &x));
 30:   PetscCall(VecSetSizes(x, n, PETSC_DECIDE));
 31:   PetscCall(VecSetFromOptions(x));

 33:   PetscCall(VecGetOwnershipRange(x, &low, NULL));
 34:   PetscCall(VecGetArray(x, &array));
 35:   for (i = 0; i < n; i++) array[i] = (PetscScalar)(i + low);
 36:   PetscCall(VecRestoreArray(x, &array));
 37:   /* PetscCall(VecView(x,PETSC_VIEWER_STDOUT_WORLD)); */

 39:   /* Test some vector functions */
 40:   PetscCall(VecAssemblyBegin(x));
 41:   PetscCall(VecAssemblyEnd(x));

 43:   PetscCall(VecGetSize(x, &N));
 44:   PetscCall(VecGetLocalSize(x, &n));

 46:   PetscCall(VecDuplicate(x, &x1));
 47:   PetscCall(VecCopy(x, x1));
 48:   PetscCall(VecEqual(x, x1, &flg));
 49:   PetscCheck(flg, PetscObjectComm((PetscObject)x), PETSC_ERR_ARG_WRONG, "x1 != x");

 51:   PetscCall(VecScale(x1, 2.0));
 52:   PetscCall(VecSet(x1, 10.0));
 53:   /* PetscCall(VecView(x1,PETSC_VIEWER_STDOUT_WORLD)); */

 55:   /* Create vector y over shared memory */
 56:   PetscCall(VecCreate(PETSC_COMM_WORLD, &y));
 57:   PetscCall(VecSetSizes(y, n, PETSC_DECIDE));
 58:   PetscCall(VecSetFromOptions(y));
 59:   PetscCall(VecGetArray(y, &array));
 60:   for (i = 0; i < n; i++) array[i] = -(PetscScalar)(i + 100 * rank);
 61:   PetscCall(VecRestoreArray(y, &array));
 62:   PetscCall(VecAssemblyBegin(y));
 63:   PetscCall(VecAssemblyEnd(y));
 64:   /* PetscCall(VecView(y,PETSC_VIEWER_STDOUT_WORLD)); */

 66:   /* Create two index sets */
 67:   if (rank == 0) {
 68:     PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 3, ix0, PETSC_COPY_VALUES, &isx));
 69:     PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 3, iy0, PETSC_COPY_VALUES, &isy));
 70:   } else {
 71:     PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 3, ix1, PETSC_COPY_VALUES, &isx));
 72:     PetscCall(ISCreateBlock(PETSC_COMM_SELF, bs, 3, iy1, PETSC_COPY_VALUES, &isy));
 73:   }

 75:   if (rank == 10) {
 76:     PetscCall(PetscPrintf(PETSC_COMM_SELF, "\n[%d] isx:\n", rank));
 77:     PetscCall(ISView(isx, PETSC_VIEWER_STDOUT_SELF));
 78:     PetscCall(PetscPrintf(PETSC_COMM_SELF, "\n[%d] isy:\n", rank));
 79:     PetscCall(ISView(isy, PETSC_VIEWER_STDOUT_SELF));
 80:   }

 82:   /* Create Vector scatter */
 83:   PetscCall(VecScatterCreate(x, isx, y, isy, &ctx));
 84:   PetscCall(VecScatterSetFromOptions(ctx));
 85:   PetscCall(VecScatterGetType(ctx, &type));
 86:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "scatter type %s\n", type));

 88:   /* Test forward vecscatter */
 89:   PetscCall(VecSet(y, 0.0));
 90:   PetscCall(VecScatterBegin(ctx, x, y, ADD_VALUES, SCATTER_FORWARD));
 91:   PetscCall(VecScatterEnd(ctx, x, y, ADD_VALUES, SCATTER_FORWARD));
 92:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "\nSCATTER_FORWARD y:\n"));
 93:   PetscCall(VecView(y, PETSC_VIEWER_STDOUT_WORLD));

 95:   /* Test reverse vecscatter */
 96:   PetscCall(VecSet(x, 0.0));
 97:   PetscCall(VecSet(y, 0.0));
 98:   PetscCall(VecGetOwnershipRange(y, &low, NULL));
 99:   PetscCall(VecGetArray(y, &array));
100:   for (i = 0; i < n; i++) array[i] = (PetscScalar)(i + low);
101:   PetscCall(VecRestoreArray(y, &array));
102:   PetscCall(VecScatterBegin(ctx, y, x, ADD_VALUES, SCATTER_REVERSE));
103:   PetscCall(VecScatterEnd(ctx, y, x, ADD_VALUES, SCATTER_REVERSE));
104:   PetscCall(PetscPrintf(PETSC_COMM_WORLD, "\nSCATTER_REVERSE x:\n"));
105:   PetscCall(VecView(x, PETSC_VIEWER_STDOUT_WORLD));

107:   /* Free objects */
108:   PetscCall(VecScatterDestroy(&ctx));
109:   PetscCall(ISDestroy(&isx));
110:   PetscCall(ISDestroy(&isy));
111:   PetscCall(VecDestroy(&x));
112:   PetscCall(VecDestroy(&x1));
113:   PetscCall(VecDestroy(&y));
114:   PetscCall(PetscFinalize());
115:   return 0;
116: }

118: /*TEST

120:    test:
121:       nsize: 2

123: TEST*/