Actual source code: ex22.c

  1: /*$Id: ex22.c,v 1.24 2001/09/11 16:32:10 bsmith Exp $*/

  3: static char help[] = "Scatters from a parallel vector to a parallel vector.\n\n";

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

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

 19:   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:   N = size*n;
 25:   VecCreate(PETSC_COMM_WORLD,&y);
 26:   VecSetSizes(y,PETSC_DECIDE,N);
 27:   VecSetFromOptions(y);
 28:   VecCreate(PETSC_COMM_WORLD,&x);
 29:   VecSetSizes(x,PETSC_DECIDE,N);
 30:   VecSetFromOptions(x);
 31:   /* create two index sets */
 32:   ISCreateStride(PETSC_COMM_WORLD,n,n*rank,1,&is1);
 33:   ISCreateStride(PETSC_COMM_WORLD,n,(n*(rank+1))%N,1,&is2);

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

 39:   VecScatterCreate(x,is1,y,is2,&ctx);
 40:   VecScatterBegin(x,y,ADD_VALUES,SCATTER_FORWARD,ctx);
 41:   VecScatterEnd(x,y,ADD_VALUES,SCATTER_FORWARD,ctx);
 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: