[petsc-users] Get global column indices thay belong to another process?

[Appel, Thibaut]

Assuming you preallocate/assemble a MPIAIJ matrix “by hand” using a ISLocalToGlobalMapping object obtained from DMDA: what’s the easiest way to get global column indices that do not belong to a process? 

Say, if you have a finite-difference stencil and the stencil exceeds the portion owned by the process.

I think the way to go is to preallocate a MPIAIJ matrix using local information with MatPreallocateSetLocal and then fill values with MatSetLocal, those routines can’t work with rows/columns not owned by the process right?

Thank you,

Thibaut