[petsc-users] A flag for FormFunction.

[Jed Brown]

On Thu, 14 Jan 2010 10:49:11 -0600, Barry Smith <bsmith at mcs.anl.gov> wrote:
>     Does this handle all situations you are thinking of?

This is definitely the right thing for my example.  The other case would
be -snes_mf_operator where part of the preconditioner is cached while
evaluating F.  But this is also not a big deal, since again, the user can

  SNESGetJacobian(snes,&A,0,0,0);
  PetscTypeCompare(A,MFFD,&flg);
  if (flg) MatMFFDSetFunction(A,FormFunctionNoCache,ctx);

Doing something different based on the call stack is a really bad thing,
I don't think FormFunction should be allowed to find out, just that any
cases that seem to call for it should have an alternate mechanism (which
they do).

Jed