[petsc-users] Configure nested PCFIELDSPLIT with general index sets

[Natacha BEREUX]

Thanks for your quick answers. To be honest, I am not familiar at all with
DMShells and DMPlexes. But since it is what I need, I am going to try it.
Thanks again  for your advices,
Natacha

On Tue, Mar 21, 2017 at 2:27 PM, Lawrence Mitchell <
lawrence.mitchell at imperial.ac.uk> wrote:

>
> > On 21 Mar 2017, at 13:24, Matthew Knepley <knepley at gmail.com> wrote:
> >
> > I think the remedy is as easy as specifying a DMShell that has a
> PetscSection (DMSetDefaultSection) with your ordering, and
> > I think this is how Firedrake (http://www.firedrakeproject.org/) does
> it.
>
> We actually don't use a section, but we do provide
> DMCreateFieldDecomposition_Shell.
>
> If you have a section that describes all the fields, then I think if the
> DMShell knows about it, you effectively get the same behaviour as DMPlex
> (which does the decomposition in the same manner?).
>
> > However, I usually use a DMPlex which knows about my
> > mesh, so I am not sure if this strategy has any holes.
>
> I haven't noticed anything yet.
>
> Lawrence
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