[dune-pdelab] Testing whether a gridfunctionspace is conforming

[Christian Engwer]

On Thu, Apr 28, 2016 at 09:19:40AM +0000, Eike Mueller wrote:
> Dear DUNE-pdelab,
> 
> is there an easy way of testing whether a given gridfunctionspace is conforming or not (i.e. discontinuous)?

No. Actually there are a couple of things you have to keep in
mind.... Either you are using something like DG, then it is quite
obvious, but it is still not easy to detect this in your code; you
might solve this by introducing some typetraits which are specialized
on different finite-element-maps. Second you could be using
Lagrange-Ansatz-Functions, but then you are still not sure that you
have a conforming space, as the grid might have hanging nodes and you
have to do extra tricks to ensure conformity; in this case you could
check teh Constraints-Assembler. But even taking all this into
account, you don't even know whether a particular space is conforming
or not, as it depends on you actual problem. If we stick to the dG
example, this is a non-conforming space for the poisson-problem, but
a dG pressure space for Navier-Stokes is conforming, as you only
require L2 for the pressure.

Now... what do actually want to know?
If you really ask for conformity, I don't see how this should impact
you code. On the other hand certain information about discontinuities
can be very helpful to avoid unnecessary computation.

Cheers
Christian

> Thanks,
> 
> Eike
> _______________________________________________
> dune-pdelab mailing list
> dune-pdelab at dune-project.org
> http://lists.dune-project.org/mailman/listinfo/dune-pdelab
> 

-- 
Prof. Dr. Christian Engwer 
Institut für Numerische und Angewandte Mathematik
Fachbereich Mathematik und Informatik der Universität Münster
Einsteinstrasse 62
48149 Münster

E-Mail  christian.engwer at uni-muenster.de
Telefon +49 251 83-35067
FAX     +49 251 83-32729