[petsc-users] MatChop

[Pierre Jolivet]

> On 21 May 2021, at 6:03 PM, Stefano Zampini <stefano.zampini at gmail.com> wrote:
> 
> Emmanuel
> 
> thanks for reporting this.
> I believe we have a regression in MatChop from https://gitlab.com/petsc/petsc/-/commit/038df967165af8ac6c3de46a36f650566a7db07c <https://gitlab.com/petsc/petsc/-/commit/038df967165af8ac6c3de46a36f650566a7db07c> (cc'ing Pierre)
> We call MatAssemblyBegin/End within the row loop. Also. I don't understand why we need to check for  r < rend herre https://gitlab.com/petsc/petsc/-/blob/038df967165af8ac6c3de46a36f650566a7db07c/src/mat/utils/axpy.c#L513 <https://gitlab.com/petsc/petsc/-/blob/038df967165af8ac6c3de46a36f650566a7db07c/src/mat/utils/axpy.c#L513>. nor why we need to allocate newCols (can use cols)

That part is from the initial 8-year old implementation from Matt (https://gitlab.com/petsc/petsc/-/commit/4325cce7191c5c61f4f090c59eaf6773fdee7b48#9d78409dea8190bffda8b68fee5aef233dc1c677 <https://gitlab.com/petsc/petsc/-/commit/4325cce7191c5c61f4f090c59eaf6773fdee7b48#9d78409dea8190bffda8b68fee5aef233dc1c677>).
You need the check otherwise this error is raised: https://www.mcs.anl.gov/petsc/petsc-current/src/mat/interface/matrix.c.html#line566 <https://www.mcs.anl.gov/petsc/petsc-current/src/mat/interface/matrix.c.html#line566>.

Thanks,
Pierre

> Pierre, can you take a look?
> 
> Il giorno ven 21 mag 2021 alle ore 18:49 Emmanuel Ayala <juaneah at gmail.com <mailto:juaneah at gmail.com>> ha scritto:
> Hi everybody,
> 
> I just updated petsc from version 13 to 15. Before the update everything works well, then my code give me an error:
> 
> [9]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
> [9]PETSC ERROR: Invalid argument
> [9]PETSC ERROR: Setting off process row 53484 even though MatSetOption(,MAT_NO_OFF_PROC_ENTRIES,PETSC_TRUE) was set
> [9]PETSC ERROR: See https://www.mcs.anl.gov/petsc/documentation/faq.html <https://www.mcs.anl.gov/petsc/documentation/faq.html> for trouble shooting.
> [9]PETSC ERROR: Petsc Release Version 3.15.0, Mar 30, 2021 
> [9]PETSC ERROR: ./comp on a arch-linux-c-opt-O2-superlud_mumps_hyp named eayala by ayala Fri May 21 10:40:36 2021
> [9]PETSC ERROR: Configure options --with-debugging=0 COPTFLAGS="-O2 -march=native -mtune=native" CXXOPTFLAGS="-O2 -march=native -mtune=native" FOPTFLAGS="-O2 -march=native -mtune=native" --download-mpich --download-hypre --download-mumps --download-scalapack --download-parmetis --download-metis --download-superlu_dist --download-cmake --download-fblaslapack=1 --with-cxx-dialect=C++11
> 
> The error appears after a matrix assembly, the matrix was created with DMCreateMatrix and updated with MatSetValuesLocal.
> 
> A Little work around I found the solution, avoid using MatChop on this matrix, but I still need to use MatChop. There is any reason to have this problem?
> 
> Thanks in advance.
> 
> 
> 
> 
> 
> 
> -- 
> Stefano

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