[petsc-users] snes fieldsplit for kkt

[Jed Brown]

Tobin Isaac <tisaac at ices.utexas.edu> writes:

> A unified interface that encompasses inequality constraints is more
> ambitious than what I had in mind for now.  What I meant when I said
> "specify the equations" was specify the first order optimality
> conditions for a problem with pure equality constraints.  Choosing
> between full-space and reduced-space would then be just choosing
> between snes strategies.

Fair enough, a SNES FieldSplit is something we've been thinking about,
but we haven't fixed an interface for decomposition. That is, we need
the analog of MatGetSubMatrix() for nonlinear systems. For the line
search, we will need to be able to use the problem structure to define
the augmented Lagrangian objective functional. So it's not something
currently available, but it's something we might be able to do in the
next release cycle (3.5) and we'd certainly like to hear your input on
how it should look.