[petsc-users] Mat local size zero

[Matthew Knepley]

On Fri, May 3, 2013 at 1:52 PM, Hui Zhang <mike.hui.zhang at hotmail.com>wrote:

> Hello,
>
> I'm implementing a coarse problem for a domain decomposition
> preconditioner.
> I use many processors to solve one subdomain and I want to pick one
> processor
> for each subdomain to solve the global coarse problem.  So I need to set
> the
> local sizes of the coarse operator on the other processors to be zero.  Is
> this a good idea?  Thanks in advance!
>

This is fine. The only drawback would be that collective operations would
still take
place over the entire communicator. If this ever becomes a problems (in a
land
far far away), you can just call MatGetSubmatrix() for that process.

   Matt

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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