Actual source code: ex4.c

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

 4:  #include petscvec.h
 5:  #include petscsys.h

  9: int main(int argc,char **argv)
 10: {
 12:   PetscMPIInt    rank;
 13:   PetscInt       n = 5,idx1[2] = {0,3},idx2[2] = {1,4};
 14:   PetscScalar    one = 1.0,two = 2.0;
 15:   Vec            x,y;
 16:   IS             is1,is2;
 17:   VecScatter     ctx = 0;

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

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

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

 33:   VecSet(x,one);
 34:   VecSet(y,two);
 35:   VecScatterCreate(x,is1,y,is2,&ctx);
 36:   VecScatterBegin(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
 37:   VecScatterEnd(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
 38:   VecScatterDestroy(ctx);
 39: 
 40:   if (!rank) {VecView(y,PETSC_VIEWER_STDOUT_SELF);}

 42:   ISDestroy(is1);
 43:   ISDestroy(is2);

 45:   VecDestroy(x);
 46:   VecDestroy(y);
 47:   PetscFinalize();

 49:   return 0;
 50: }