Actual source code: ex23.c


  2: static char help[] = "Scatters from a parallel vector to a sequential vector.\n\
  3:   Using a blocked send and a strided receive.\n\n";

  5: /*
  6:         0 1 2 3 | 4 5 6 7 ||  8 9 10 11

  8:      Scatter first and third block to first processor and
  9:      second and third block to second processor
 10: */

 12: #include <petscvec.h>

 14: int main(int argc,char **argv)
 15: {
 16:   PetscInt       i,blocks[2],nlocal;
 17:   PetscMPIInt    size,rank;
 18:   PetscScalar    value;
 19:   Vec            x,y;
 20:   IS             is1,is2;
 21:   VecScatter     ctx = 0;
 22:   PetscViewer    subviewer;

 24:   PetscInitialize(&argc,&argv,(char*)0,help);
 25:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 26:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);


 30:   /* create two vectors */
 31:   if (rank == 0) nlocal = 8;
 32:   else nlocal = 4;
 33:   VecCreate(PETSC_COMM_WORLD,&x);
 34:   VecSetSizes(x,nlocal,12);
 35:   VecSetFromOptions(x);
 36:   VecCreate(PETSC_COMM_SELF,&y);
 37:   VecSetSizes(y,8,PETSC_DECIDE);
 38:   VecSetFromOptions(y);

 40:   /* create two index sets */
 41:   if (rank == 0) {
 42:     blocks[0] = 0; blocks[1] = 2;
 43:   } else {
 44:     blocks[0] = 1; blocks[1] = 2;
 45:   }
 46:   ISCreateBlock(PETSC_COMM_SELF,4,2,blocks,PETSC_COPY_VALUES,&is1);
 47:   ISCreateStride(PETSC_COMM_SELF,8,0,1,&is2);

 49:   for (i=0; i<12; i++) {
 50:     value = i;
 51:     VecSetValues(x,1,&i,&value,INSERT_VALUES);
 52:   }
 53:   VecAssemblyBegin(x);
 54:   VecAssemblyEnd(x);

 56:   VecScatterCreate(x,is1,y,is2,&ctx);
 57:   VecScatterBegin(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
 58:   VecScatterEnd(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
 59:   VecScatterDestroy(&ctx);

 61:   PetscViewerGetSubViewer(PETSC_VIEWER_STDOUT_WORLD,PETSC_COMM_SELF,&subviewer);
 62:   VecView(y,subviewer);
 63:   PetscViewerRestoreSubViewer(PETSC_VIEWER_STDOUT_WORLD,PETSC_COMM_SELF,&subviewer);

 65:   VecDestroy(&x);
 66:   VecDestroy(&y);
 67:   ISDestroy(&is1);
 68:   ISDestroy(&is2);

 70:   PetscFinalize();
 71:   return 0;
 72: }

 74: /*TEST

 76:    testset:
 77:       nsize: 2
 78:       output_file: output/ex23_1.out
 79:       filter: grep -v "  type:"
 80:       diff_args: -j
 81:       test:
 82:         suffix: standard
 83:         args: -vec_type standard
 84:       test:
 85:         requires: cuda
 86:         suffix: cuda
 87:         args: -vec_type cuda
 88:       test:
 89:         requires: viennacl
 90:         suffix:  viennacl
 91:         args: -vec_type viennacl
 92:       test:
 93:         requires: !sycl kokkos_kernels
 94:         suffix: kokkos
 95:         args: -vec_type kokkos
 96:       test:
 97:         requires: hip
 98:         suffix: hip
 99:         args: -vec_type hip

101: TEST*/