Actual source code: ex12.c

  1: /*$Id: ex12.c,v 1.51 2001/09/11 16:32:10 bsmith Exp $*/

  3: static char help[] = "Scatters from a sequential vector to a parallel vector.n
  4: This does case when we are merely selecting the local part of then
  5: parallel vector.n";

 7:  #include petscvec.h
 8:  #include petscsys.h

 10: int main(int argc,char **argv)
 11: {
 12:   int           n = 5,ierr,size,rank,i;
 13:   PetscScalar   value;
 14:   Vec           x,y;
 15:   IS            is1,is2;
 16:   VecScatter    ctx = 0;

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

 20:   MPI_Comm_size(PETSC_COMM_WORLD,&size);
 21:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);

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

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

 33:   /* each processor inserts the entire vector */
 34:   /* this is redundant but tests assembly */
 35:   for (i=0; i<n; i++) {
 36:     value = (PetscScalar) (i + 10*rank);
 37:     VecSetValues(y,1,&i,&value,INSERT_VALUES);
 38:   }
 39:   VecAssemblyBegin(y);
 40:   VecAssemblyEnd(y);

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

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

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