[petsc-dev] resurrecting the finite element energy functions thread

[Geoffrey Irving]

After a brief delay, I'm back to needing finite element energy
functions for optimization problems.  The original thread is

    http://lists.mcs.anl.gov/pipermail/petsc-dev/2013-December/014161.html

That thread veered off into some more general discussions of the
PetscFE API, and I don't think came to a specific conclusion as to the
best way to add said energy functions.  In terms of API, what is
missing is a function to integrate a function over a space, where the
functions takes various field arguments and produces one or more
scalars.  The quadrature rule is important: in my case there will be
only one non-auxiliary field, and the integration function needs to
use the same quadrature rule.

I apologize if I failed to read through the previous discussion
correctly, and/or the required function has already been written.  If
not, I'm happy to mock something up, ideally with function signature
suggestions from others first.

Thanks,
Geoffrey