> The new code is in https://gitlab.com/petsc/petsc/-/merge_requests/7293 and
> retains the null space on the submatrices for both MatZeroRows() and
> MatZeroRowsAndColumns() regardless of changes to the nonzero structure of the
> matrix.
Thank you very much Barry.
It works as expected.
--
j
Hi Barry
> The bug fix for 2 is availabel in
> https://gitlab.com/petsc/petsc/-/merge_requests/7279
Note that our code goes through MatZeroRowsColumns_MPIAIJ() not through
MatZeroRows_MPIAIJ() so this fix does not change anything for the case I
mentioned.
--
jeremy
> > Because of a combination of settings, our code passes through this line:
> >
> > https://gitlab.com/petsc/petsc/-/blob/main/src/ksp/pc/impls/fieldsplit/fieldsplit.c?ref_type=heads#L692
> >
> > i.e. the matrices associated with each of the sub-KSPs of a fieldsplit are
> > destroyed and then re-
Hi all
Because of a combination of settings, our code passes through this line:
https://gitlab.com/petsc/petsc/-/blob/main/src/ksp/pc/impls/fieldsplit/fieldsplit.c?ref_type=heads#L692
i.e. the matrices associated with each of the sub-KSPs of a fieldsplit are
destroyed and then re-created later.
just in case it helps, here's one way I have to create the near nullspace:
https://github.com/seamplex/feenox/blob/main/src/pdes/mechanical/init.c#L468
--
jeremy
From: petsc-users on behalf of Jordi Manyer
Fuertes via petsc-users
Sent: Tuesday, December 5, 2023
Thanks. That worked.
--
jeremy
From: Jacob Faibussowitsch
Sent: Tuesday, June 13, 2023 11:25 AM
To: Jeremy Theler (External)
Cc: petsc-users
Subject: Re: [petsc-users] Start logging with -info after PetscInitialize()
[External Sender]
Call PetscInfoDestroy
Hello all.
I've asked this question to Satish personally last week at the conference, but
I'm stuck so any help would be appreciated.
For some reason not worth explaining, I need to activate -info after
PetscInitialize() has been already called.
I'm trying something like this:
PetscOptionsSetVa
r.
> Anyway, sorry for the changes.
> I hate changing GAMG for this reason and I hate AMG for this reason!
No need to apologize, I just want to better understand how to better
exploit your code!
Thanks
--
jeremy
>
> Thanks,
> Mark
>
>
>
> On Thu, Apr 13, 2023 at 8:17
the stiffness matrix. It is a refined version of the NAFEMS
LE10 benchmark described here:
https://seamplex.com/feenox/examples/mechanical.html#nafems-le10-thick-plate-pressure-benchmark
If you want, I could dump the matrix, rhs and near nullspace vectors
and share them.
--
jeremy theler
thres
The default smoothing PC changed from sor to jacobi in 3.17. The
Changelog says the old behavior can be recovered by using
-mg_levels_pc_type sor.
1. Is there a way to set the mg_levels_pc_type via an API call?
2. Are there any changes in efficiency expected with this new PC?
Regards
--
jeremy
I've known at least one other person that had this very same confusion.
Maybe it's worth adding Barry's explanation to the manual page:
This function can be called BEFORE PetscInitialize(), but it does not
NEED to be called before PetscInitialize(). You should be able to call
PetscOptionsSetValue(
wer_hdf5_default_timestepping
>
> I think that is what you want.
I'd like to rely on PetscViewerHDF5SetDefaultTimestepping() to provide
backwards compatibility as well. This branch has been merged into
master back in November but never made it to the stable v3.16 releases.
Can you guys check please?
Thanks
--
jeremy theler
www.seamplex.com
Hola Jesús
You were lucky you got 20x. See
https://petsc.org/release/docs/manualpages/Mat/MatSeqAIJSetPreallocation.html
https://petsc.org/release/docs/manualpages/Mat/MatMPIAIJSetPreallocation.html
Quote:
"For large problems you MUST preallocate memory or you will get
TERRIBLE performance, see
On Fri, 2021-12-10 at 10:02 +0100, Quentin Chevalier wrote:
> root@container:/home/shared# echo $PETSCH_ARCH $PETSCH_DIR
PETSCH_ARCH -> PETSC_ARCH
PETSCH_DIR -> PETSC_DIR
On Thu, 2020-09-24 at 18:30 -0400, Matthew Knepley wrote:
> > There is also DMPlexFindVertices() which finds the nearest vertex
> > to
> > > the given coords in the given radius.
> >
> > At first I had understood that this function performed a nearest-
> > neighbor search but after a closer look i
n a full sweep over the DM.
Thanks
--
jeremy
>
> Thanks,
>
> Vaclav
>
> > On 16 Sep 2020, at 01:44, Matthew Knepley
> > wrote:
> >
> > On Tue, Sep 15, 2020 at 6:18 PM Jeremy Theler
> > wrote:
> > > On Mon, 2020-09-14 at 20:28 -0400,
On Mon, 2020-09-14 at 20:28 -0400, Matthew Knepley wrote:
> On Mon, Sep 14, 2020 at 6:15 PM Jeremy Theler
> wrote:
> > Hello all
> >
> > Say I have a fully-interpolated 3D DMPlex and a point with
> > arbitrary
> > coordinates x,y,z. What's the most effici
Hello all
Say I have a fully-interpolated 3D DMPlex and a point with arbitrary
coordinates x,y,z. What's the most efficient way to know which cell
this point belongs to in parallel? Cells can be either tets or hexes.
Regards
--
jeremy theler
www.seamplex.com
The usual trick is to set ones in one matrix and zeros in the other
one.
On Mon, 2020-02-17 at 12:35 -0600, Emmanuel Ayala wrote:
> Hi everyone,
>
> I have an eigenvalue problem where I need to apply BCs to the
> stiffness and mass matrix.
>
> Usually, for KSP solver, it is enough to set to ze
On Thu, 2020-01-30 at 18:05 -0500, Matthew Knepley wrote:
> On Thu, Jan 30, 2020 at 6:04 PM Jeremy Theler
> wrote:
> > On Thu, 2020-01-30 at 21:10 +, Smith, Barry F. wrote:
> >
> > > MatGetSubMatrix() and then do the product on the sub matrix
> > then
&
On Thu, 2020-01-30 at 21:10 +, Smith, Barry F. wrote:
> MatGetSubMatrix() and then do the product on the sub matrix then
> VecSum
>
Ok, I have it working in a single-processor and throws the expected
value. Yet I have a segfault in parallel when I ask for the IS
corresponding to the rows
tiply
each of them by the vector and then add the scalars up. Or, conversely,
sum all the rows colmunwise and then multiply the sum by a vector.
How can I do this?
Regards
--
jeremy theler
www.seamplex.com
?
PetscScalar e;
Vec Kx;
VecDuplicate(x, &Kx);
MatMult(K, x, Kx);
VecDot(x, Kx, &e);
--
jeremy theler
www.seamplex.com
,
if memory is used until just before a process exits, don’t free it
simply to silence such a tool.
Regards
--
jeremy theler
www.seamplex.com
On Tue, 2020-01-21 at 08:49 -0800, Sam Guo wrote:
> I use PETSc from my application. Sounds you are saying I just treat
> ierr!=0 as an system err
describes the methods and not just the implementation as
the source code at gamg/util.c so I can better understand what is going
on.
Thanks
--
Jeremy Theler
www.seamplex.com
On Thu, 2017-01-05 at 09:18 -0500, Mark Adams wrote:
> You want the bottom of page 84 in the manual.
>
> On W
* Any reference to what pc_gamg_treshold means and/or does?
On Wed, 2017-01-04 at 18:13 -0300, Jeremy Theler wrote:
> Hi! Any reference to what does -pc_gamg_threshold mean and/or?
>
Hi! Any reference to what does -pc_gamg_threshold mean and/or?
--
Jeremy Theler
www.seamplex.com
when I ask
MatGetNearNullSpace(matrix) passing the problem matrix after setting
PCSetCoordinates(pc) I get:
error: PETSc error 85-0 'Null Object: Parameter # 1'
in /home/gtheler/libs/petsc-3.7.4/src/mat/interface/matnull.c
MatNullSpaceGetVecs:64
thanks
--
Jeremy Theler
www.seamplex.com
On Mon, 2016-10-31 at 08:44 -0600, Jed Brown wrote:
> > After understanding Matt's point about the near nullspace (and reading
> > some interesting comments from Jed on scicomp stackexchange) I did built
> > my own vectors (I had to take a look at MatNullSpaceCreateRigidBody()
> > because I found
stretched?
>
> Do this again with these parameters:
>
> -mg_levels_ksp_type chebyshev
> -mg_levels_esteig_ksp_type cg
> -mg_levels_esteig_ksp_max_it 10
>
> -mg_levels_ksp_chebyshev_esteig 0,.1,0,1.05
> -gamg_est_ksp_type cg
>
>
> On Fri, Oct 28, 2016 at 9:48 AM, Jeremy Theler
>
On Fri, 2016-10-28 at 09:46 -0400, Mark Adams wrote:
> Please run with -info and grep on GAMG.
>
[0] PCSetUp_GAMG(): level 0) N=120726, n data rows=3, n data cols=6,
nnz/row (ave)=41, np=1
[0] PCGAMGFilterGraph(): 99.904% nnz after filtering, with
threshold 0., 13.7468 nnz ave. (N=40242)
[
>
> If I do not call PCSetCoordinates() the error goes away but
> convergence
> is slow.
> Is it possible that your coordinates lie on a 2D surface? All this
> does is make the 6 basis vectors
> for translations and rotations. You can just make these yourself and
>
think there is something wrong with your matrix. Use any solver and
> verify that you like the solution first.
>
> On Fri, Oct 28, 2016 at 9:13 AM, Jeremy Theler
> wrote:
> Hi! I want to use PCGAMG as a preconditioner for a 3D linear
> elasticity
> proble
Hi! I want to use PCGAMG as a preconditioner for a 3D linear elasticity
problem (displacement-based FEM formulation) over an unstructured grid.
I am not using DMPlex, I just build the stiffness matrix myself and pass
it to PETSc.
I set MatSetBlockSize() to 3 and pass the node coordinates through
P
multiply this matrix by
> the solution vector you will get a "short" vector that on each process
> contains the "reaction" for each each of the "removed row" on that process.
>
>Easy to implement.
>
>Barry
>
> > On Oct 19, 2016,
thing with MatGetRow() that seems to work but it
is some lame I am even embarrased of sharing with the list what I have
done.
Any suggestion is welcome.
Thanks
--
jeremy theler
www.seamplex.com
I once made a quick hack, maybe you can start your dirty work from here
https://bitbucket.org/wasora/wasora/src/5a88abbac1a846f2a6ed0b4e585f6f3c0fedf2e7/m4/petsc.m4?at=default&fileviewer=file-view-default
--
jeremy
On Tue, Oct 11, 2016 at 5:31 PM Barry Smith wrote:
>
>You don't want to get
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