[petsc-users] strange error by changing the number of cells.

[Matthew Knepley]

On Tue, Dec 18, 2018 at 5:23 AM Yann JOBIC via petsc-users <
petsc-users at mcs.anl.gov> wrote:

> Le 18/12/2018 à 03:01, Matthew Knepley a écrit :
>
> On Mon, Dec 17, 2018 at 4:24 PM Yann Jobic via petsc-users <
> petsc-users at mcs.anl.gov> wrote:
>
>> Dear petsc users,
>>
>> I'm using petsc FEM framework, with p4est. I'm getting a strange error,
>> when changing the number of point in DMPlexCreateBoxMesh() (2D, 20x20 is
>> ok, 22x22 is not) :
>>
>> [0]PETSC ERROR: Nonconforming object sizes
>> [0]PETSC ERROR: The section point closure size 20 != dual space dimension
>> 18
>>
>
> Okay, here is what the nomenclature means. The closure size is the size I
> get from the Section
> when I take the closure of the given point. So for example, if we have
> quads and Q2 elements,
> that would have a closure size of
>
>   3 x 3 = 9
>
> per component. So a 2-component Q2 element would have closure size 18. The
> dual space
> dimension is the number of dual space basis vectors. If we use a Lagrange
> element, there
> would be 1 dof per vertex, 1 per edge and 1 per cell for quadratic fields,
> so on a quad that is
> 9 dofs, and for 2 component fields that is 18. This is why the two numbers
> are designed to match.
> Could you give
>
>   -petscds_view
>
> so I can see the element you are using, and also PetscSectionView() on the
> DM section (or use
> -petscsection_view although that catches all sections, so it hard to find
> the right one).
>
>   Thanks,
>
> The problem arise in parallel, and for a 6x6 grid size. I'm doing
> something wrong, but i don't know where. It's working fine in older petsc
> version.
> You will find in attachment the log files.
>
> The code for the section is the following :
>     ierr = DMGetSection(dmAux,&section);CHKERRQ(ierr);
>     PetscSectionView(section, PETSC_VIEWER_STDOUT_WORLD);
>
> Thanks for the help !
>

On 1 proc, you have 120 cells, but on 2 procs you have 126? Can you also
send the output with -dm_view?
I can't see what is going on with the parallelization. Are you specfiying
some overlap in the partition?

  Thanks,

    Matt


> Yann
>
>
>     Matt
>
>
>> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html
>> for trouble shooting.
>> [0]PETSC ERROR: Petsc Release Version 3.10.2, Oct, 09, 2018
>> [0]PETSC ERROR: ./gauss on a  named crabe by yann Mon Dec 17 22:17:38 2018
>> [0]PETSC ERROR: Configure options
>> --prefix=/local/lib/petsc/3.10/p2/gcc/openmpi_gcc_all
>> --with-single-library=0 --with-debugging=1 --download-scalapack=1
>> --download-metis=1 --download-parmetis=1 --download-ptscotch=1
>> --download-mumps=1 --download-hypre=1 --download-superlu=1
>> --download-superlu_dist=1 --download-fblaslapack=1 --download-metis=1
>> --download-ml=1 --download-p4est=1 --download-netcdf=1
>> --download-pragmatic=1 --with-cxx-dialect=C++11 --download-eigen=1
>> --download-parms=1 --download-triangle=1 --download-hdf5=1 --with-zlib=1
>> --download-szlib=1 --download-suitesparse=1 --with-shared-libraries=0
>> PETSC_ARCH=openmpi_gcc_all
>> [0]PETSC ERROR: #1 DMProjectLocal_Generic_Plex() line 400 in
>> /local/yann/petsc-3.10.2/src/dm/impls/plex/plexproject.c
>> [0]PETSC ERROR: #2 DMProjectFunctionLocal_Plex() line 530 in
>> /local/yann/petsc-3.10.2/src/dm/impls/plex/plexproject.c
>> [0]PETSC ERROR: #3 DMProjectFunctionLocal() line 6320 in
>> /local/yann/petsc-3.10.2/src/dm/interface/dm.c
>> [0]PETSC ERROR: #4 DMProjectFunctionLocal_p4est() line 4393 in
>> /local/yann/petsc-3.10.2/src/dm/impls/forest/p4est/pforest.c
>> [0]PETSC ERROR: #5 DMProjectFunctionLocal() line 6320 in
>> /local/yann/petsc-3.10.2/src/dm/interface/dm.c
>> [0]PETSC ERROR: #6 SetupVelocity() line 332 in
>> /local/yann/fe-utils/petsc/3.10/gauss.c
>> [0]PETSC ERROR: #7 SetupVelBC() line 359 in
>> /local/yann/fe-utils/petsc/3.10/gauss.c
>> [0]PETSC ERROR: #8 main() line 652 in
>> /local/yann/fe-utils/petsc/3.10/gauss.c
>>
>> I'm using petscspace_degree == 2 for the primary field, and also for the
>> auxiliary one (velocity). The error occurs when i project the velocity
>> function into the auxiliary field.
>>
>> Do you see where the problem could come from ?
>>
>> Best regards,
>>
>> Yann
>>
>>
>

-- 
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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