Actual source code: ex24.c


  2: static char help[] = "Scatters from a parallel vector to a sequential vector.\n\
  3: Tests where the local part of the scatter is a copy.\n\n";

  5: #include <petscvec.h>

  7: int main(int argc,char **argv)
  8: {
  9:   PetscMPIInt    size,rank;
 10:   PetscInt       n = 5,i,*blks,bs = 1,m = 2;
 11:   PetscScalar    value;
 12:   Vec            x,y;
 13:   IS             is1,is2;
 14:   VecScatter     ctx = 0;
 15:   PetscViewer    sviewer;

 17:   PetscInitialize(&argc,&argv,(char*)0,help);

 19:   PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);
 20:   PetscOptionsGetInt(NULL,NULL,"-bs",&bs,NULL);

 22:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 23:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);

 25:   /* create two vectors */
 26:   VecCreate(PETSC_COMM_WORLD,&x);
 27:   VecSetSizes(x,PETSC_DECIDE,size*bs*n);
 28:   VecSetFromOptions(x);

 30:   /* create two index sets */
 31:   if (rank < size-1) m = n + 2;
 32:   else m = n;

 34:   PetscMalloc1(m,&blks);
 35:   blks[0] = n*rank;
 36:   for (i=1; i<m; i++) blks[i] = blks[i-1] + 1;
 37:   ISCreateBlock(PETSC_COMM_SELF,bs,m,blks,PETSC_COPY_VALUES,&is1);
 38:   PetscFree(blks);

 40:   VecCreateSeq(PETSC_COMM_SELF,bs*m,&y);
 41:   ISCreateStride(PETSC_COMM_SELF,bs*m,0,1,&is2);

 43:   /* each processor inserts the entire vector */
 44:   /* this is redundant but tests assembly */
 45:   for (i=0; i<bs*n*size; i++) {
 46:     value = (PetscScalar) i;
 47:     VecSetValues(x,1,&i,&value,INSERT_VALUES);
 48:   }
 49:   VecAssemblyBegin(x);
 50:   VecAssemblyEnd(x);
 51:   VecView(x,PETSC_VIEWER_STDOUT_WORLD);

 53:   VecScatterCreate(x,is1,y,is2,&ctx);
 54:   VecScatterBegin(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
 55:   VecScatterEnd(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);

 57:   PetscViewerASCIIPushSynchronized(PETSC_VIEWER_STDOUT_WORLD);
 58:   PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_WORLD,"----\n");
 59:   PetscViewerGetSubViewer(PETSC_VIEWER_STDOUT_WORLD,PETSC_COMM_SELF,&sviewer);
 60:   VecView(y,sviewer)); fflush(stdout;
 61:   PetscViewerRestoreSubViewer(PETSC_VIEWER_STDOUT_WORLD,PETSC_COMM_SELF,&sviewer);
 62:   PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD);
 63:   PetscViewerASCIIPopSynchronized(PETSC_VIEWER_STDOUT_WORLD);

 65:   VecScatterDestroy(&ctx);

 67:   VecDestroy(&x);
 68:   VecDestroy(&y);
 69:   ISDestroy(&is1);
 70:   ISDestroy(&is2);

 72:   PetscFinalize();
 73:   return 0;
 74: }

 76: /*TEST

 78:    testset:
 79:       nsize: 3
 80:       output_file: output/ex24_1.out
 81:       filter: grep -v "  type:"
 82:       test:
 83:         suffix: standard
 84:         args: -vec_type standard
 85:       test:
 86:         requires: cuda
 87:         suffix: cuda
 88:         args: -vec_type cuda
 89:       test:
 90:         requires: viennacl
 91:         suffix:  viennacl
 92:         args: -vec_type viennacl

 94: TEST*/