On Fri, Feb 3, 2012 at 08:07, Klaij, Christiaan
<C.Klaij@marin.nl> wrote:
> I should add a MatNestGetISs() so you can get out the automatically-created
> ISs. They will have the structure described below. If you want to work with
> the released version, you should create the ISs yourself.
As a user, having MatNestGetISs would be most convenient.
Pushed to petsc-dev, you have to allocate arrays to hold the returned ISs.
> A has a contigous distribution, so the ISs must respect that. Did you try
> creating the index sets described above? Please explain "something's wrong".
Finally I understand the relation between the nesting and the
index sets. After replacing my incorrect ISs with the correct
ones, everything's fine (no more [0]PETSC ERROR: Arguments are
incompatible! [0]PETSC ERROR: Could not find index set!).
Thanks a lot for your help, Jed, I really appreciate it.