[petsc-users] local Vec to global Vec and global 3-D array

[Barry Smith]

On May 15, 2013, at 2:25 PM, Roc Wang <pengxwang at hotmail.com> wrote:

> Thanks, I will write the stand alone code for it. One more question about the global and local vector below.
> 
> > > > > ierr = DMCreateGlobalVector(da,&gsol3d);CHKERRQ(ierr);
> > > > > ierr = DMLocalToGlobalBegin(da,x,INSERT_VALUES,gsol3d);CHKERRQ(ierr);
> > > > > ierr = DMLocalToGlobalEnd(da,x,INSERT_VALUES,gsol3d);CHKERRQ(ierr);
> > > > 

    In the above you are trying to scatter a local vector x to a global vector gsol3d. But x is a global vector. 

> 
> !*******************************
> The x from KSPGetSolution() IS a global vector, it is not a "local" vector? (It should be a typo :) )

   It is a global vector.

>  So Can I convert the global x to a 3d array directly? Thank. 

   You can convert either a global vector or a local vector to 3d array access BUT the converted global vector has NO ghost values accessible while the converted local vector has ghost points available (after the call to DMGlobalToLocalBegin/End()).



>