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
