[petsc-dev] MatSetColoring

[Jed Brown]

Peter Brune <prbrune at gmail.com> writes:

> https://bitbucket.org/petsc/petsc/commits/all/tip/prbrune/snes-jacobiancolorfixchanges

Bitbucket website seems screwed up, but 'git fetch' still works.

> setting user coloring back to how it was in 3.3; I'll change the
> manual to describe why this is bad (doesn't work with grid sequencing or
> FAS or a number of other things) and then merge into maint if it's OK.

Is the context ever set in current code, with the expectation that it
will be ignored?  Maybe when used with TS?  In any case, the branch
should cook in 'next' before being merged to 'maint'.

It's probably worth risking the low-probability of a user depending on
the parameter being ignored in exchange for being able to fix this
inconvenience in petsc-3.4.

Or MatSetColoring() could be revived for 3.4.1 and then you wouldn't
have to worry about breaking compatibility.

> After that, we should take MatGetColoring and MatSetColoring and make them
> be a convenient interface.  Can we remove the remaining Adifor stuff and
> start from scratch on this?

I don't think the Adifor stuff was being kept intentionally.

> Having a good parallel MatColoring would make a lot of these problems less
> severe.  We should write a simple one and then go from there.

Yes.