static char help[] = "Demonstrates various vector routines for DMDA.\n\n";

/*
  Include "petscpf.h" so that we can use pf functions and "petscdmda.h" so
 we can use the PETSc distributed arrays
*/

#include <petscpf.h>
#include <petscdm.h>
#include <petscdmda.h>

PetscErrorCode myfunction(void *ctx,PetscInt n,const PetscScalar *xy,PetscScalar *u)
{
  PetscInt i;

  PetscFunctionBeginUser;
  for (i=0; i<n; i++) {
    u[2*i]   = xy[2*i];
    u[2*i+1] = xy[2*i+1];
  }
  PetscFunctionReturn(0);
}

int main(int argc,char **argv)
{
  Vec            u,xy;
  DM             da;
  PetscInt       m = 10, n = 10, dof = 2;
  PF             pf;

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc,&argv,(char*)0,help));
  PetscCall(DMDACreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE,DMDA_STENCIL_BOX,m,n,PETSC_DECIDE,PETSC_DECIDE,dof,1,0,0,&da));
  PetscCall(DMSetFromOptions(da));
  PetscCall(DMSetUp(da));
  PetscCall(DMDASetUniformCoordinates(da,0.0,1.0,0.0,1.0,0.0,1.0));
  PetscCall(DMCreateGlobalVector(da,&u));
  PetscCall(DMGetCoordinates(da,&xy));

  PetscCall(DMDACreatePF(da,&pf));
  PetscCall(PFSet(pf,myfunction,0,0,0,0));
  PetscCall(PFSetFromOptions(pf));

  PetscCall(PFApplyVec(pf,xy,u));

  PetscCall(VecView(u,PETSC_VIEWER_DRAW_WORLD));

  /*
     Free work space.  All PETSc objects should be destroyed when they
     are no longer needed.
  */
  PetscCall(VecDestroy(&u));
  PetscCall(PFDestroy(&pf));
  PetscCall(DMDestroy(&da));
  PetscCall(PetscFinalize());
  return 0;
}

/*TEST

   test:

TEST*/