dolfin team mailing list archive

["Robert C. Kirby" <kirby@xxxxxxxxxxxx>]

You most definitely don't want to use the d-1 dimensional element of  
the same type.  Works great for Lagrange (and actually Hermite, for  
what it's worth), but is disastrously catastrophic for everything else.


On Apr 12, 2006, at 8:29 AM, Garth N. Wells wrote:

> On Wed, 2006-04-12 at 15:09 +0200, Garth N. Wells wrote:
> > On Wed, 2006-04-12 at 14:30 +0200, Johan Hoffman wrote:
> >
> > > Apart from the issue of duplicating code with or without  
> > > templates, what
> > > do we need to figure out to get the assembly of boundary integrals
> > > correct?
> > >
> > > Do we have a clear way to obtain the FE basis for the boundary of  
> > > a cell
> > > given the basis of the cell? Do we use the corresponding basis  
> > > for for d-1
> > > dimensions?
> > >
> > > /Johan
> >
> > This will have to come from FFC won't it? It might be less efficient,
> > but we could work with the finite element of the whole cell and  
> > perhaps
> > the edge/face number is enough for FFC to do the rest.
>
> Thinking about this some more, it might be better not to restrict the
> finite element basis to the boundary in order to work with problems
> where derivatives of the basis functions appear in the boundary
> integrals, and hence involve all nodes of the element. Similar  
> story for
> non-conforming elements.
>
> Garth
>
>
> > I noticed that
> > the FFC-produced function eval takes "unsigned int boundary" as an
> > argument, but doesn't do anything with it yet.
> >
> > Garth
> >
> >
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