Actual source code: ex13.c

  2: static char help[] = "Scatters from a sequential vector to a parallel vector.  In\n\
  3: this case each local vector is as long as the entire parallel vector.\n";

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

 10: int main(int argc,char **argv)
 11: {
 13:   PetscInt       n = 5,i,N;
 14:   PetscMPIInt    size,rank;
 15:   PetscScalar    value;
 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,0,1,&is2);

 35:   for (i=0; i<N; i++) {
 36:     value = (PetscScalar) i;
 37:     VecSetValues(x,1,&i,&value,INSERT_VALUES);
 38:   }
 39:   VecAssemblyBegin(x);
 40:   VecAssemblyEnd(x);

 42:   VecScatterCreate(x,is2,y,is1,&ctx);
 43:   VecScatterBegin(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
 44:   VecScatterEnd(ctx,x,y,INSERT_VALUES,SCATTER_FORWARD);
 45:   VecScatterDestroy(ctx);
 46: 
 47:   VecView(y,PETSC_VIEWER_STDOUT_WORLD);

 49:   VecDestroy(x);
 50:   VecDestroy(y);
 51:   ISDestroy(is1);
 52:   ISDestroy(is2);

 54:   PetscFinalize();
 55:   return 0;
 56: }
 57: