On Aug 15, 2012, at 1:03 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> On Tue, Aug 14, 2012 at 5:03 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> But you've just told me that ONLY ts is allowed to use the SNESSetJacobian()
> context slot (coloring and presumably users) aren't allowed to.
>
> Not at all. I mean that coloring as produced internally by SNES should not
> ascribe special meaning to that field being NULL or not. You could perhaps
> have -snes_fd_color create an empty coloring object and put it into the
> callback slowt. We should perhaps support destructors for function/Jacobian
> contexts.
I think it uses null in order to delay computing the matrix coloring etc
from the time of SNESSetJacobian() to a later time. I guess what could happen
is it creates a n "empty" fdcoloring beast and passes that into
SNESSetJacobian() and then fills it up later when it has the information it
needs.
Barry
