[petsc-users] restricted DMDAGlobaltoLocal

[Hui Zhang]

> On Nov 21, 2011, at 8:01 AM, Jed Brown wrote:
> 
>> On Mon, Nov 21, 2011 at 04:52, Hui Zhang <buyong.huier at gmail.com> wrote:
>> When using DMDAGlobaltoLocal, how can I communicate only the boundary of the
>> ghosted domain (with stecil width larger than one)?
>> 
>> Only the ghost values are communicated. The interior is all local.
> 
>   I think Hui means DMDALocalToLocalBegin() and DMDALocalToLocalEnd() but normally one doesn't need this with the PETSc solvers, one only needs the DMGlobalToLocalBegin/End()
> 
>   Barry
> 

Thank you all!

I'm actually implementing domain decomposition methods with restricted communication.
From my understanding, DMDALocalToLocalXX is also communicating all ghost values of 
the second Vec. However, in a restricted way, only the ghost points most far away from
the interior are communicated.