Actual source code: ex14.c

  2: static char help[] = "Scatters from a sequential vector to a parallel vector.\n\
  3: This does the tricky case.\n\n";

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

 10: int main(int argc,char **argv)
 11: {
 13:   PetscInt       n = 5,N;
 14:   PetscMPIInt    size,rank;
 15:   PetscScalar    value,zero = 0.0;
 16:   Vec            x,y;
 17:   IS             is1,is2;
 18:   VecScatter     ctx = 0;

 20:   PetscInitialize(&argc,&argv,(char*)0,help);
 21:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 22:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);

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

 31:   /* create two index sets */
 32:   ISCreateStride(PETSC_COMM_SELF,n,0,1,&is1);
 33:   ISCreateStride(PETSC_COMM_SELF,n,rank,1,&is2);

 35:   value = rank+1;
 36:   VecSet(x,value);
 37:   VecSet(y,zero);

 39:   VecScatterCreate(x,is1,y,is2,&ctx);
 40:   VecScatterBegin(ctx,x,y,ADD_VALUES,SCATTER_FORWARD);
 41:   VecScatterEnd(ctx,x,y,ADD_VALUES,SCATTER_FORWARD);
 42:   VecScatterDestroy(ctx);
 43: 
 44:   VecView(y,PETSC_VIEWER_STDOUT_WORLD);

 46:   VecDestroy(x);
 47:   VecDestroy(y);
 48:   ISDestroy(is1);
 49:   ISDestroy(is2);

 51:   PetscFinalize();
 52:   return 0;
 53: }
 54: