[petsc-users] DMPlex SF

[Matthew Knepley]

On Sat, Apr 4, 2026 at 1:15 PM Miguel Molinos <m.molinos at upm.es> wrote:

> Dear all,
>
> For a given cell in a local patch of a distributed DMPlex mesh, is there
> a way to retrieve the list of ranks that share that same cell?
>
It is somewhat involved. Each process that does not own the cell will know
the owner. You will know how many processes also have the cell using
PetscSFComputeRootDegree(), however you will not have the rank. You can use
PetscSFGather() to get the ranks, and then Bcast that to the leaf
processes. This pattern creates the two-sided information. We do this
inside VecScatter, and I guess we could expose that. Junchao would know
that better than I would.

 Thanks,

    Matt

> Thanks,
>
> Miguel
>


-- 
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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