MatGetSubMatrix question

Jed Brown jed at
Tue May 26 13:02:07 CDT 2009

Lisandro Dalcin wrote:

> unless things have changed very recently (after 3.0.0 release), IS is
> far from being a real parallel object.

What exactly do you mean by this?  It has a parallel communicator and
collective operations.  ISGetIndices gives you just the local indices,
with size given by ISGetLocalSize, but ISGetSize gives you the global
size, ISInvertPermutation is collective (not scalable, but that's
another issue), etc.  The row IS given to MatGetSubMatrix is parallel.


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