Date: 2013-07-02T14:40:11+00:00

Actual source code: ex4.c
petsc-3.4.2 2013-07-02

      2: static char help[] = "Scatters from a parallel vector into seqential vectors.\n\n";

      4: #include <petscvec.h>

      8: int main(int argc,char **argv)
      9: {
     11:   PetscMPIInt    rank;
     12:   PetscInt       n   = 5,idx1[2] = {0,3},idx2[2] = {1,4};
     13:   PetscScalar    one = 1.0,two = 2.0;
     14:   Vec            x,y;
     15:   IS             is1,is2;
     16:   VecScatter     ctx = 0;

     18:   PetscInitialize(&argc,&argv,(char*)0,help);
     19:   PetscOptionsGetInt(NULL,"-n",&n,NULL);
     20:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);

     22:   /* create two vectors */
     23:   VecCreate(PETSC_COMM_WORLD,&x);
     24:   VecSetSizes(x,n,PETSC_DECIDE);
     25:   VecSetFromOptions(x);
     26:   VecCreateSeq(PETSC_COMM_SELF,n,&y);

     28:   /* create two index sets */
     29:   ISCreateGeneral(PETSC_COMM_SELF,2,idx1,PETSC_COPY_VALUES,&is1);
     30:   ISCreateGeneral(PETSC_COMM_SELF,2,idx2,PETSC_COPY_VALUES,&is2);

     32:   VecSet(x,one);
     33:   VecSet(y,two);
     34:   VecScatterCreate(x,is1,y,is2,&ctx);
     35:   VecScatterBegin(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
     36:   VecScatterEnd(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
     37:   VecScatterDestroy(&ctx);

     39:   if (!rank) {VecView(y,PETSC_VIEWER_STDOUT_SELF);}

     41:   ISDestroy(&is1);
     42:   ISDestroy(&is2);

     44:   VecDestroy(&x);
     45:   VecDestroy(&y);
     46:   PetscFinalize();

     48:   return 0;
     49: }