ffc team mailing list archive

["Garth N. Wells" <g.n.wells@xxxxxxxxxx>]

Anders Logg wrote:
> On Mon, Dec 04, 2006 at 02:14:51PM +0100, Garth N. Wells wrote:
> > Could we add something to FFC to describe where the various degrees of 
> > freedom live (on vertices, edges, internal)?
> >
> > Garth
>
> Yes we could, but I'd rather not. Why do we need it? I'd prefer if
> DOLFIN did not know anything about dofs, other than how to reorder
> them.

Not sure that it's this simple if you want to assemble some terms 
block-wise. Also, for parallel assembly we might need to know where dofs 
lie. I'm still thinking about this so I can't be concrete in what's 
needed just yet.

> I see two options:
>
>  1. Reorder the dofs computed by FFC, not knowing why and how they
>     are numbered.

This is one option I'm considering. Just take the FFC numbering, and run 
a renumbering algorithm over it to minimise bandwidth.

>  2. Compute a different mapping in FFC.

This could be difficult as it depends on properties of the mesh, 
partition, etc. I think that this should remain simple.

> I can be convinced otherwise of course, but I don't understand why
> this is needed.
>
> /Anders
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