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

[Matthew Knepley]

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,

    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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