[petsc-users] DMPlexDistributeField

Matthew Knepley knepley at gmail.com
Sun Jul 7 20:48:59 CDT 2019

On Sun, Jul 7, 2019 at 8:37 PM Adrian Croucher <a.croucher at auckland.ac.nz>

> hi Matt,
> On 29/06/19 12:07 AM, Matthew Knepley wrote:
> Okay, I ran through this. I am attaching my C version which was easier for
> me to play with in the debugger, but it should not be
> hard to put the few lines into yours. The problem comes from using overlap
> in the redistribution. You can see this by running
>   mpiexec -n 2 ./distgeom2 -overlap 1 -overlap2 0
> which works fine. If overlap2 is 1, then the face data is shifted.
> Yes, that's the same thing I found.
> Something in DistributeField() does not know that we changed
> the topology after we distributed by adding overlap cells. This is strange
> since DMPlexMigrate() works on the coordinates for
> the overlapped mesh, however they always start at 0 in the vector, so it
> must be that some offset is missing. I am looking for it now.
> It looked to me like the problem might lie not in DMPlexDistributeField()
> but in DMPlexDistribute(), because if you view the redistribution SF coming
> out of the second call to DMPlexDistribute() it looks wrong.
> DMPlexDistributeField() appeared to be doing what it was told, but the SF
> it was given didn't look right to me.
> True. I fixed it, but I am just getting the PR in order. Should have it
tomorrow morning.



> - Adrian
> --
> Dr Adrian Croucher
> Senior Research Fellow
> Department of Engineering Science
> 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

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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