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

  4: /*T
  5:    Concepts: mathematical functions
  6:    Processors: n
  7: T*/

  9: /*
 10:   Include "petscpf.h" so that we can use pf functions and "petscdmda.h" so
 11:  we can use the PETSc distributed arrays
 12: */

 14:  #include <petscpf.h>
 15:  #include <petscdm.h>
 16:  #include <petscdmda.h>

 18: PetscErrorCode myfunction(void *ctx,PetscInt n,const PetscScalar *xy,PetscScalar *u)
 19: {
 20:   PetscInt i;

 23:   for (i=0; i<n; i++) {
 24:     u[2*i]   = xy[2*i];
 25:     u[2*i+1] = xy[2*i+1];
 26:   }
 27:   return(0);
 28: }

 30: int main(int argc,char **argv)
 31: {
 32:   Vec            u,xy;
 33:   DM             da;
 35:   PetscInt       m = 10, n = 10, dof = 2;
 36:   PF             pf;

 38:   PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
 39:   DMDACreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE,DMDA_STENCIL_BOX,m,n,PETSC_DECIDE,PETSC_DECIDE,dof,1,0,0,&da);
 40:   DMSetFromOptions(da);
 41:   DMSetUp(da);
 42:   DMDASetUniformCoordinates(da,0.0,1.0,0.0,1.0,0.0,1.0);
 43:   DMCreateGlobalVector(da,&u);
 44:   DMGetCoordinates(da,&xy);

 46:   DMDACreatePF(da,&pf);
 47:   PFSet(pf,myfunction,0,0,0,0);
 48:   PFSetFromOptions(pf);

 50:   PFApplyVec(pf,xy,u);

 52:   VecView(u,PETSC_VIEWER_DRAW_WORLD);

 54:   /*
 55:      Free work space.  All PETSc objects should be destroyed when they
 56:      are no longer needed.
 57:   */
 58:   VecDestroy(&u);
 59:   PFDestroy(&pf);
 60:   DMDestroy(&da);
 61:   PetscFinalize();
 62:   return ierr;
 63: }