ufl team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Tue, Oct 30, 2007 at 10:06:10AM +0100, Martin Sandve Alnæs wrote:
> 2007/10/30, kent-and@xxxxxxxxx <kent-and@xxxxxxxxx>:
> > > On Fri, Oct 26, 2007 at 12:03:06PM +0200, Martin Sandve Alnæs wrote:
> > >
> > >> I talked with Pearu a little bit yesterday about SymPy and our
> > >> requirements for UFL. We might consider building UFL on top of SymPy.
> > >> That would give us a lot of symbolic functionality for free, and it
> > >> seems to be rather easy to extend with our own specialized objects.
> > >> (In that case, we should use the newer sympycore version, not the
> > >> current tip). If something is missing, we have Pearu at hand to extend
> > >> SymPy.
> > >>
> > >> http://code.google.com/p/sympy/
> > >> http://code.google.com/p/sympycore/
> > >>
> > >> But lets start with defining what we want UFL to be.
> > >
> > > My feeling is that our needs for a symbolic engine is quite
> > > small. Even if UFL will be able to handle more than FFC, the FFC form
> > > language is just about 700 lines of Python (including comments, see
> > > algebra.py).
> > >
> > > But let's leave it open. It would be good if we could avoid
> > > dependencies, but if we find ourselves reimplementing a lot of things
> > > from SymPy then why not use it.
> > >
> > > /Anders
> >
> > ok, lets start defining it and then consider SymPy later.
> >
> > Kent
> 
> Ok. A backside of using SymPy is that we don't have control over its
> development, and we won't be able to freeze its syntax the same way we
> can with our own UFL.
> 
> I think the most complicated features that are missing from my
> prototype code that we need are tensor notation which ffc already has,
> and differentiation wrt userdefined variables which ffc doesn't have.
> 
> I want to implement automatic computation of the Jacobi form J(v,u; w)
> from F(v; w) within the UFL framework, which should be very
> interesting for the fenics goal "automation of mathematical
> modelling", don't you think?

Yes, definitely.

/Anders