ffc team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Martin Sandve Alnæs wrote:
> 2008/12/6 Garth N. Wells <gnw20@xxxxxxxxx>:
> > It would be useful if we could somehow associate names with mixed
> > functions, e.g.
> >
> >   P2 = VectorElement("Lagrange", "triangle", 2)
> >   P1 = FiniteElement("Lagrange", "triangle", 1)
> >   TH = P2 + P1
> >   (u, p, "U") = Functions(TH)
> >
> > so that in the DOLFIN-specific C++ wrapper code we can use
> >
> >   a.U = u;
> >
> > to attach mixed functions rather than
> >
> >   a.w0 = u;
> >   a.w1 = v;
> >   etc.
> >
> > which is error prone. Andy suggestions on a nice way to do this in the
> > FFC input? Will this be part of UFL?
> >
> > Garth
>
> I get the problem and idea, but I don't get this code example. You
> can't assign to "U".

The example isn't a suggestion, just an illustration that I would 
somehow like to associate the name "U" with the mixed function.

> Also, I think we should remove "Functions" from UFL, using "split"
> explicitly instead:
>
> U = Function(TH)
> u, p = split(u)
>
> then we will have:
>
> a.U = u; // mixed function
>
> in the dolfin code.

That would be nice.

> We can add a name attribute to Function in UFL, but I
> removed this a short while ago to keep things simple...
> Then this would do the same:
>
> u, p = split(Function(TH, name="U"))

The first of your examples look simpler to me.

Garth

> --
> Martin