The plex way is to use the transitive closure https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/DMPLEX/DMPlexGetTransitiveClosure.html and filter out points you are not interested in. See for example https://gitlab.com/petsc/petsc/-/blob/master/src/dm/impls/plex/plex.c#L828 and https://gitlab.com/petsc/petsc/-/blob/master/src/dm/impls/plex/plex.c#L833
Il giorno lun 22 feb 2021 alle ore 14:28 Fabien Vergnet < [email protected]> ha scritto: > Dear PETSc community, > > Thank you for your amazing work. I discovered PETSc recently and I need > your help for a project. > > As a training, I would like to assemble the Finite Element Matrix for the > Poisson problem on a part of my mesh. So, I create a DMPlex from a .msh > file and I create a Submesh with > > DMPlexCreateSubmesh(dm, label, 1, PETSC_TRUE, &subdm); > > In order to assemble my Finite Element Matrix, I need to iterate over the > cells of the mesh (which are triangles) and identify the vertices > composing each cell. > > My question is the following : how can I get, for each cell, the vertices > composing the cell ? > > I have tried to uninterpolate the subdm with DMPlexUninterpolate (with > the objective to get the vertices from DMPlexGetCone) but it does not > seem to work for a Submesh since I get the following error: > > ---------- > > [0]PETSC ERROR: --------------------- Error Message > -------------------------------------------------------------- > [0]PETSC ERROR: Invalid argument > [0]PETSC ERROR: Not for partially interpolated meshes > [0]PETSC ERROR: See https://www.mcs.anl.gov/petsc/documentation/faq.html > for trouble shooting. > [0]PETSC ERROR: Petsc Release Version 3.14.4, Feb 03, 2021 > [0]PETSC ERROR: Configure options > --prefix=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/petsc-3.14.4-xtae5tcwlzkb4oiifbayj77bqlz5nngk > --with-ssl=0 --download-c2html=0 --download-sowing=0 --download-hwloc=0 > CFLAGS= FFLAGS= CXXFLAGS= > --with-cc=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/openmpi-4.0.5-ygn7zymoy7crl7b4xsdkc4zmfojugmdy/bin/mpicc > --with-cxx=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/openmpi-4.0.5-ygn7zymoy7crl7b4xsdkc4zmfojugmdy/bin/mpic++ > --with-fc=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/openmpi-4.0.5-ygn7zymoy7crl7b4xsdkc4zmfojugmdy/bin/mpif90 > --with-precision=double --with-scalar-type=real --with-shared-libraries=1 > --with-debugging=0 --with-64-bit-indices=0 COPTFLAGS= FOPTFLAGS= > CXXOPTFLAGS= > --with-blaslapack-lib=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/openblas-0.3.13-6b3u6zc5j4hvauqh3ldcwnf7lm2o4vyl/lib/libopenblas.so > --with-x=0 --with-clanguage=C --with-scalapack=0 --with-cuda=0 > --with-metis=1 > --with-metis-dir=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/metis-5.1.0-lm3k7dh2vslghqtqc6dvcpnc54bfpqq2 > --with-hypre=1 > --with-hypre-dir=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/hypre-2.20.0-4pyxhku65wb5lmh2fpflhmjmow2pbjg7 > --with-parmetis=1 > --with-parmetis-dir=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/parmetis-4.0.3-pfiam4ccxkyqpapejcdjtlyr6cyz7irc > --with-mumps=0 --with-trilinos=0 --with-fftw=0 --with-valgrind=0 > --with-gmp=0 --with-libpng=0 --with-giflib=0 --with-mpfr=0 --with-netcdf=0 > --with-pnetcdf=0 --with-moab=0 --with-random123=0 --with-exodusii=0 > --with-cgns=0 --with-memkind=0 --with-p4est=0 --with-saws=0 --with-yaml=0 > --with-libjpeg=0 --with-cxx-dialect=C++11 > --with-superlu_dist-include=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/superlu-dist-6.4.0-bagymefhq7s7gerf7jxwiv4fv7szoljh/include > --with-superlu_dist-lib=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/superlu-dist-6.4.0-bagymefhq7s7gerf7jxwiv4fv7szoljh/lib/libsuperlu_dist.a > --with-superlu_dist=1 --with-suitesparse=0 --with-ptscotch=0 > --with-hdf5-include=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/hdf5-1.10.7-dkfs4ir3hlahyfs5z4xcmsf4ogklimji/include > --with-hdf5-lib=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/hdf5-1.10.7-dkfs4ir3hlahyfs5z4xcmsf4ogklimji/lib/libhdf5.so > --with-hdf5=1 > --with-zlib-include=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/zlib-1.2.11-2pwsgfxppopolmjj6tf34k5jsaqzpodo/include > --with-zlib-lib=/users/home/vergnet/apps/spack/opt/spack/linux-ubuntu20.04-zen2/gcc-9.3.0/zlib-1.2.11-2pwsgfxppopolmjj6tf34k5jsaqzpodo/lib/libz.so > --with-zlib=1 > [0]PETSC ERROR: #1 DMPlexUninterpolate() line 1514 in > /tmp/vergnet/spack-stage/spack-stage-petsc-3.14.4-xtae5tcwlzkb4oiifbayj77bqlz5nngk/spack-src/src/dm/impls/plex/plexinterpolate.c > [0]PETSC ERROR: #2 assemble_mass() line 59 in > /users/home/vergnet/codes/cilia/cilia/cpp/assembling.hpp > > ---------- > > Attached are a minimal working example, a mesh file and a makefile. > > Any ideas or suggestions are more than welcome ! > > Regards, > Fabien > > > > -- Stefano
