[petsc-dev] MatSetColoring

[Barry Smith]

On May 17, 2013, at 3:25 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> 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.

   Actually it was being kept because it unlike ADIC Adifor actually works.

> 
>> 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.