Re: [Libmesh-devel] Easy way to combine finite elements?

[Stogner, R. H <roy...@ic...>]

On Tue, 9 Apr 2019, Paul T. Bauman wrote:

> Is there an easy way to take existing finite elements and combine them? I'm interested in trying out  an augmented Taylor-Hood element (P2/P1+P0)
> where basically I'm just adding a constant to the P1 pressure space. It would be nice to be able to do this without having to implement all the
> methods for a new finite element object, but wasn't sure if anyone had done this before or would know if it's possible.

This sounds like a great idea but there's definitely no way to do it
right now.

What would worry me the most about adding it is that we have too much
critical functionality implemented in "switch statements in
FEInterface" form, which might have efficiency advantages but is
practically impossible to extend at runtime.  A FEComposite subclass
could handle virtual function responses on the fly but there's got to
be a couple hundred FEInterface uses which would have to be upgraded,
probably also adding some cost to performance (for object
construction, not just for virtual function vs switch statement) in
the common case.
---
Roy