ufl team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Mon, Feb 23, 2009 at 02:05:00PM +0100, Martin Sandve Alnæs wrote:
> On Mon, Feb 23, 2009 at 12:36 PM, Anders Logg <logg@xxxxxxxxx> wrote:
> > On Mon, Feb 23, 2009 at 11:51:42AM +0100, Martin Sandve Alnæs wrote:
> >> Looks ok, but I simplified it further.
> >
> > Looks nice and simple.
> >
> >> Note that we might need a more sofisticated renumbering
> >> later, to discover that e.g. u[i]*v[i] and u[j]*v[j] are the
> >> same expression, for fast optimization of quadrature code.
> >
> > ok
> >
> >> Also, I moved the argument renumbering to FormData,
> >> take a look at it. I've removed the "classes" and
> >> "*_renumbering" members of FormData. We should
> >> go through the FormData structure soon to finalize
> >> it as well as we can.
> >
> > I wasn't aware that FormData already did some renumbering. What does
> > it renumber and how does it relate to renumber_indices?
> 
> It didn't renumber anything, what I removed was a numbering mapping,
> mapping each function to its place in the form in [0,n).
> But now it renumbers the form arguments (not the indices).
> It has to apply expand_derivatives before this, since
> this can result in changes in the argument list.
> (I don't really like this, see the FIXME comment in formdata.py).
> The current implementation of expand_derivatives calls expand_compounds.
> 
> If you make a formdata:
> 
>   fd = FormData(a)
> 
> You get e.g. a list of functions:
> 
>   fd.coefficients
> 
> which have counts in [0,n),
> and can get the original argument (e.g. the PyDOLFIN Function)
> from the dict original_arguments:
> 
>   for f in fd.coefficients:
>       original_f = fd.original_arguments[f]

ok.

> >> I've confusingly used the term "coefficient" in e.g.
> >> FormData, I guess we should stick to "function" in UFL.
> >> Agreed?
> >
> > Agree, but there will be a coefficient thing in the monomial
> > representation where functions are expanded to
> >
> >  f = f_i v_i
> 
> Do you need to represent this sum explicitly?
> Some extension to UFL will be needed to do that.

No, implicitly via indices.

-- 
Anders

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