[petsc-dev] Bug in MatZeroRows_MPIAIJ

[Stefano Zampini]

I think that the test

if ((diag != 0.0) && (mat->A->rmap->N == mat->A->cmap->N)) {

at line 836 in src/mat/impls/aij/mpi/mpiaij.c (master) is a bug, either for rectangular matrices or even for square matrices with non-trivial layouts.

It can happen that some of the processes does not satisfy the test and some others do; in this case, MatAssemblyBegin/End is not  collectively called.

I don’t see any trivial fix; my solution involves computing a flag during MatSetSizes() based on some test on the ranges of the row and column layouts.
I will go on and fix it in a branch unless someone has a simpler solution.





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