[petsc-users] transfer vector data diagonally on DA

[khalid ashraf]

Hi Jed,

I am using petsc/3.1 and the include file "petscdmda.h" is not working. I am using the "petscda.h"
and DACreate3D. 
unew_localptr[][][] is from a global vector using VecGetArray
u_localptr[][][] is from a local vector communicated from a global vector.
I tried 
unew_localptr[k][j][i]=u_localptr[k-1][j-1][i-1]

but it gives Segmentation Violation error. 
I also tried unew_localptr[k][j][i]=u_localptr[k][j+1][i+1] which works but 
unew_localptr[k][j][i]=u_localptr[k+1][j+1][i+1] or unew_localptr[k][j][i]=u_localptr[k][j-1][i-1]
does not work. I am running the program on4 processors.


Thanks.


  ierr = DACreate3d(PETSC_COMM_WORLD,DA_YPERIODIC,DA_STENCIL_BOX,appctx.l,appctx.m,appctx.n,
                    PETSC_DECIDE,PETSC_DECIDE,PETSC_DECIDE,1,1,PETSC_NULL,PETSC_NULL,PETSC_NULL,
                    &appctx.da);CHKERRQ(ierr);
 for (k=zs; k<zs+zm; k++) {
  for (j=ys; j<ys+ym; j++) {
  for (i=xs; i<xs+xm; i++) {

  if(i!=0 || j!=0 || k!=0|| i!=mx-1 || j!=my-1 || k!=mz-1)

  unew_localptr[k][j][i]=u_localptr[k+1][j+1][i+1];

}}}

________________________________
 From: Jed Brown <jedbrown at mcs.anl.gov>
To: khalid ashraf <khalid_eee at yahoo.com>; PETSc users list <petsc-users at mcs.anl.gov> 
Sent: Sunday, April 1, 2012 10:07 PM
Subject: Re: [petsc-users] transfer vector data diagonally on DA
 

On Sun, Apr 1, 2012 at 22:01, khalid ashraf <khalid_eee at yahoo.com> wrote:

I want to transfer vector data diagonally in the DA grid like 
> for (k=zs; k<zs+zm; k++) {
>  for (j=ys; j<ys+ym; j++) {
>  for (i=xs; i<xs+xm; i++) {
>if(i!=mx-1 || j!=my-1 || k!=mz-1){
>u_new[k+1][j+1][i+1]=u[k][j][i];}
>}}}
>
>
>Could you please suggest the best way to do it minimizing interprocessor assignments.

Both are on the same DMDA?

Communicate U to Ulocal (DMGlobalToLocalBegin/End) using a BOX stencil with width at least 1, get the global array u_new[][][] from UGlobalNew and the local arrays u[][][] from Ulocal, then assign u_new[k][j][i] = u[k-1][j-1][i-1].
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