[petsc-users] Parallel Graph Coloring

[Gaetan Kenway]

Hi

I have a quick question regarding the MatGetColoring() function. According
to the documentation,

 "For parallel matrices currently converts to sequential matrix and uses
the sequential coloring on that."

I am wondering does this give actually give a valid parallel coloring? My
application is a cell centered multi-block finite volume code, (with
block-based decomposition)  and the communications are done using a two
level exchange of halo cells. I would like to use FD (actually forward mode
AD to compute the jacbian matrix). So, what I'm wondering is, if a cell
with color 0 is perturbed on processor 0, is it guaranteed that a residual
on processor 1, that is influenced by the 0-colored cell on proc zero is
*only* influenced by the color 0 from proc 0 and not a 0-colored cell on
proc 1?

I hope that is clear

Thank you,

Gaetan Kenway
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