[petsc-users] Question about DMLocalToLocal when using DM_BOUNDARY_GHOSTED

[Lucas Banting]

Hello,

I am converting a serial code to parallel in fortran with petsc. I am using the DMDA to manage communication of the information that used to be in old two-dimensional fortran arrays.

I noticed when using DMLocalToLocalBegin/End, not all the ghost values in the array at the DM_BOUNDARY_GHOSTED area is updated. Is this expected behaviour?
I read through this thread: https://lists.mcs.anl.gov/mailman/htdig/petsc-users/2016-May/029252.html and saw someone had a similar question, but the answer was not clear to me.

If this is expected behaviour, how should I instead update these values in my arrays? I was using DM_BOUNDARY_GHOSTED as I needed the extra ghost cells for some subroutines, but I do not need them in my matrix from DMCreateMatrix.

I am using Petsc 3.12.4 and open MPI 3.1.4.

Thanks,

Lucas Banting

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