[petsc-dev] ISRestoreNonlocalIS?

[Barry Smith]

On Nov 18, 2010, at 4:32 PM, Jed Brown wrote:

> On Thu, Nov 18, 2010 at 23:27, Barry Smith <bsmith at mcs.anl.gov> wrote:
> But will this be true for all uses of ISAllGather() (or any new name given it) in the future?
> 
> I think ISAllGather() only makes sense if you are requesting something at least partly redundant.  I don't know why you would want to extract e.g. a matrix living on a global comm where each proc (or subcomm) has a full redundant copy.

  MatGetRedundantMatrix() which is used by PCREDUNDANT which is very useful doing multigrid when you want to solve the coarse problems on subsets of processes :-)

   Barry

> 
> Jed