Actual source code: ex33.c


  2: static char help[] = "Tests the routines VecScatterCreateToAll(), VecScatterCreateToZero()\n\n";

  4: #include <petscvec.h>

  6: int main(int argc, char **argv)
  7: {
  8:   PetscInt    n = 3, i, len, start, end;
  9:   PetscMPIInt size, rank;
 10:   PetscScalar value, *yy;
 11:   Vec         x, y, z, y_t;
 12:   VecScatter  toall, tozero;

 14:   PetscFunctionBeginUser;
 15:   PetscCall(PetscInitialize(&argc, &argv, (char *)0, help));
 16:   PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
 17:   PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));

 19:   /* create two vectors */
 20:   PetscCall(VecCreateMPI(PETSC_COMM_WORLD, PETSC_DECIDE, size * n, &x));

 22:   /* each processor inserts its values */

 24:   PetscCall(VecGetOwnershipRange(x, &start, &end));
 25:   for (i = start; i < end; i++) {
 26:     value = (PetscScalar)i;
 27:     PetscCall(VecSetValues(x, 1, &i, &value, INSERT_VALUES));
 28:   }
 29:   PetscCall(VecAssemblyBegin(x));
 30:   PetscCall(VecAssemblyEnd(x));
 31:   PetscCall(VecView(x, PETSC_VIEWER_STDOUT_WORLD));

 33:   PetscCall(VecScatterCreateToAll(x, &toall, &y));
 34:   PetscCall(VecScatterBegin(toall, x, y, INSERT_VALUES, SCATTER_FORWARD));
 35:   PetscCall(VecScatterEnd(toall, x, y, INSERT_VALUES, SCATTER_FORWARD));
 36:   PetscCall(VecScatterDestroy(&toall));

 38:   /* Cannot view the above vector with VecView(), so place it in an MPI Vec
 39:      and do a VecView() */
 40:   PetscCall(VecGetArray(y, &yy));
 41:   PetscCall(VecGetLocalSize(y, &len));
 42:   PetscCall(VecCreateMPIWithArray(PETSC_COMM_WORLD, 1, len, PETSC_DECIDE, yy, &y_t));
 43:   PetscCall(VecView(y_t, PETSC_VIEWER_STDOUT_WORLD));
 44:   PetscCall(VecDestroy(&y_t));
 45:   PetscCall(VecRestoreArray(y, &yy));

 47:   PetscCall(VecScatterCreateToAll(x, &tozero, &z));
 48:   PetscCall(VecScatterBegin(tozero, x, z, INSERT_VALUES, SCATTER_FORWARD));
 49:   PetscCall(VecScatterEnd(tozero, x, z, INSERT_VALUES, SCATTER_FORWARD));
 50:   PetscCall(VecScatterDestroy(&tozero));
 51:   if (rank == 0) PetscCall(VecView(z, PETSC_VIEWER_STDOUT_SELF));
 52:   PetscCall(VecDestroy(&z));

 54:   PetscCall(VecScatterCreateToZero(x, &tozero, &z));
 55:   PetscCall(VecScatterBegin(tozero, x, z, INSERT_VALUES, SCATTER_FORWARD));
 56:   PetscCall(VecScatterEnd(tozero, x, z, INSERT_VALUES, SCATTER_FORWARD));
 57:   PetscCall(VecScatterDestroy(&tozero));
 58:   PetscCall(VecDestroy(&z));

 60:   PetscCall(VecDestroy(&x));
 61:   PetscCall(VecDestroy(&y));

 63:   PetscCall(PetscFinalize());
 64:   return 0;
 65: }

 67: /*TEST

 69:    test:
 70:       nsize: 4

 72: TEST*/