On Mon, Dec 2, 2013 at 4:49 PM, Jed Brown <[email protected]> wrote:
> Matthew Knepley <[email protected]> writes: > > So these elements are C1? I would have a tendency to fall back on mixed > > formulations or interior penalty (I don't understand these) formulations > for > > this. Then C0 elements are alright. > > C^1 elements can be delicate beasts, though they wouldn't be hard to > express now. Second derivatives would be useful even for C^0 elements, > to evaluate some error estimators and to provide stabilization terms > like SUPG (with high-order elements). > > I have always disliked having separate tiny functions for each of the > entries. Once you add second derivatives, it is painfully obvious that > humans will not be coding all those tiny functions, at which point it is > clearly not the right interface. > I do not find this argument convincing, and I don't think its coherent above. Are you proposing to merge f0/f1/f2? That seems untenable since we must test against different things, unless you want one fat functions with f0/f1/f2 as arguments. That does not seem any simpler to me. If you mean you do not want separate functions by field, I also do not agree. The indexing between fields can get very ugly inside, and we have no good user support for that. Matt -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener
