Hi Matt
We are trying to do a simple FE using DMPlex, but when assemble the global
stiffness matrix we get in problems when running NP>1 - that is the global
matrix differs when we move to a distributed system, where it should not.
In pseudo-code our CreateGlobalStiffnessMatrix does the following
create a local stiffness matrix ke with some values
for each local cell/element e (using result from DMPlexGetHeightStratum(..,0,..)
for each of its vertices (using DMPlexGetTransitiveClosure(..,e,..)
set local/global mapping to edof
update the global stiffness matrix K using the local mapping edof and values ke
The code we have sent is a simplified version, which just builds a dummy
stiffness matrix - but we believe this matrix should still the same independent
of NP. (That is why we use trace).
I'm not familiar with MatSetValuesClosure(). Is that the missing piece?
Kind regards,
Morten
________________________________
From: Matthew Knepley [[email protected]]
Sent: Monday, September 26, 2016 2:19 PM
To: Morten Nobel-Jørgensen
Cc: PETSc [[email protected]]
Subject: Re: [petsc-users] DMPlex problem
On Mon, Sep 26, 2016 at 7:00 AM, Morten Nobel-Jørgensen
<[email protected]<mailto:[email protected]>> wrote:
Hi Matthew
It seems like the problem is not fully fixed. I have changed the code to now
run on with both 2,3 and 4 cells. When I run the code using NP = 1..3 I get
different result both for NP=1 to NP=2/3 when cell count is larger than 2.
Do you mean the trace? I have no idea what you are actually putting in.
I have a lot of debugging when you use, MatSetValuesClosure(), but when you
directly use
MatSetValuesLocal(), you are handling things yourself.
Thanks,
Matt
Kind regards,
Morten
____
mpiexec -np 1 ./ex18k
cells 2
Loc size: 36
Trace of matrix: 132.000000
cells 3
Loc size: 48
Trace of matrix: 192.000000
cells 4
Loc size: 60
Trace of matrix: 258.000000
mpiexec -np 2 ./ex18k
cells 2
Loc size: 24
Loc size: 24
Trace of matrix: 132.000000
cells 3
Loc size: 36
Loc size: 24
Trace of matrix: 198.000000
cells 4
Loc size: 36
Loc size: 36
Trace of matrix: 264.000000
mpiexec -np 3 ./ex18k
cells 2
Loc size: 24
Loc size: 24
Loc size: 0
Trace of matrix: 132.000000
cells 3
Loc size: 24
Loc size: 24
Loc size: 24
Trace of matrix: 198.000000
cells 4
Loc size: 36
Loc size: 24
Loc size: 24
Trace of matrix: 264.000000
________________________________
From: [email protected]<mailto:[email protected]>
[[email protected]<mailto:[email protected]>] on
behalf of Morten Nobel-Jørgensen [[email protected]<mailto:[email protected]>]
Sent: Sunday, September 25, 2016 11:15 AM
To: Matthew Knepley
Cc: PETSc [[email protected]<mailto:[email protected]>]
Subject: Re: [petsc-users] DMPlex problem
Hi Matthew
Thank you for the bug-fix :) I can confirm that it works :)
And thanks for your hard work on PETSc - your work is very much appreciated!
Kind regards,
Morten
________________________________
From: Matthew Knepley [[email protected]<mailto:[email protected]>]
Sent: Friday, September 23, 2016 2:46 PM
To: Morten Nobel-Jørgensen
Cc: PETSc [[email protected]<mailto:[email protected]>]
Subject: Re: [petsc-users] DMPlex problem
On Fri, Sep 23, 2016 at 7:45 AM, Matthew Knepley
<[email protected]<mailto:[email protected]>> wrote:
On Fri, Sep 23, 2016 at 3:48 AM, Morten Nobel-Jørgensen
<[email protected]<mailto:[email protected]>> wrote:
Dear PETSc developers
Any update on this issue regarding DMPlex? Or is there any obvious workaround
that we are unaware of?
I have fixed this bug. It did not come up in nightly tests because we are not
using MatSetValuesLocal(). Instead we
use MatSetValuesClosure() which translates differently.
Here is the branch
https://bitbucket.org/petsc/petsc/branch/knepley/fix-dm-ltog-bs
and I have merged it to next. It will go to master in a day or two.
Also, here is the cleaned up source with no memory leaks.
Matt
Also should we additionally register the issue on Bitbucket or is reporting the
issue on the mailing list enough?
Normally we are faster, but the start of the semester was hard this year.
Thanks,
Matt
Kind regards,
Morten
________________________________
From: Matthew Knepley [[email protected]<mailto:[email protected]>]
Sent: Friday, September 09, 2016 12:21 PM
To: Morten Nobel-Jørgensen
Cc: PETSc [[email protected]<mailto:[email protected]>]
Subject: Re: [petsc-users] DMPlex problem
On Fri, Sep 9, 2016 at 4:04 AM, Morten Nobel-Jørgensen
<[email protected]<mailto:[email protected]>> wrote:
Dear PETSc developers and users,
Last week we posted a question regarding an error with DMPlex and multiple dofs
and have not gotten any feedback yet. This is uncharted waters for us, since we
have gotten used to an extremely fast feedback from the PETSc crew. So - with
the chance of sounding impatient and ungrateful - we would like to hear if
anybody has any ideas that could point us in the right direction?
This is my fault. You have not gotten a response because everyone else was
waiting for me, and I have been
slow because I just moved houses at the same time as term started here. Sorry
about that.
The example ran for me and I saw your problem. The local-tp-global map is
missing for some reason.
I am tracking it down now. It should be made by DMCreateMatrix(), so this is
mysterious. I hope to have
this fixed by early next week.
Thanks,
Matt
We have created a small example problem that demonstrates the error in the
matrix assembly.
Thanks,
Morten
--
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
--
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
--
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
--
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
