[petsc-dev] DMPlex overlap redistribution

[Matthew Knepley]

On Tue, Mar 12, 2024 at 10:54 PM Adrian Croucher <a.croucher at auckland.ac.nz>
wrote:

> hi Matt,
> On 13/03/24 12:46 pm, Matthew Knepley wrote:
>
>
> Thanks for finding this. This was indeed rewritten because the old
> algorithm was too expensive at large sizes/parallelism. The function where
> this breaks in DMPlexStratifyMigrationSF() in plexdistribute.c. The problem
> is here:
>
>
> https://urldefense.us/v3/__https://gitlab.com/petsc/petsc/-/blob/main/src/dm/impls/plex/plexdistribute.c?ref_type=heads*L915__;Iw!!G_uCfscf7eWS!b93MXLwVh7WzmrZGtcTjZj7LmqjAhvMfOsFfAR0K2HGAYkmtYwV6tX3JQNqKgsYs1hGSy-WlP60zCRikArTs$ 
>
> I treat DM_POLYTOPE_INTERIOR_GHOST as a cell no matter what. We need to
> assign the interior  vertices, faces, and edges types that will give back
> the right dimension. Vertices are easy, they should just be type POINT. I
> can understand not wanting to use SEGMENT or QUAD for the interior edge and
> face because they do not have full cones. However, I think nothing will
> break (except explicit checks, which will not work anyway) if you give them
> types SEGMENT and QUAD. Is this easy to try?
>
> Great, I just tried that and it does appear to work. I had thought there
> was a reason I'd set those types to interior ghost, but it seems to be ok
> just making them point, segment and quadrilateral.
>
> It now also works even without the modification you just made to avoid
> trouble with the depth label. So that was probably a red herring after all.
>
> Great! I am glad it's working. I will find another reason to come out for
a visit :)

  Thanks,

      Matt

> Thanks!
>
> - Adrian
>
> --
> Dr Adrian Croucher
> Senior Research Fellow
> Department of Engineering Science
> Waipapa Taumata Rau / University of Auckland, New Zealand
> email: a.croucher at auckland.ac.nz
> tel: +64 (0)9 923 4611
>
>

-- 
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

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