On Thu, Jun 2, 2016 at 5:11 PM, Luc Berger-Vergiat <lb2...@columbia.edu> wrote:
> Hi all, > I would like a quick clarification on what is and is_local are > representing in the PCASMSetLocalSubdomains(). > My understanding is that if I have two mpi ranks and four subdomains I can > end up having four blocks that I can denote as follows: > > | domain1 | domain2 | domain3 | domain3 | > rank1 | block11 | block12 | block13 | | > rank2 | block21 | block22 | -- | block24 | > > to each blockIJ I associate isIJ. > > So for rank1 I will have is=[1,2,3] and is_local=[is11,is12,is13], and for > rank2 I will have is=[1,2,4] and is_local=[is21,is22,is24]. > Or am I not understanding things correctly? I did not understand the above. The best way to think of this is algebraically. Suppose you have a matrix A, and you divide the rows into k disjoint sets where each process gets one set. Then is_local on each process is a list of the rows in that set. Now we also allow some overlap, which means rows in other sets are also used. The is on each process contains both is_local and these extra rows from other sets. Thanks, Matt > > -- > Best, > Luc > > > -- 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