Dear Roy,

Thanks a lot. It really helps. We should add those comments to the wiki and keep it updated.

So there is no class support Lagrange based discontinuous polynomial space? If the answer is no, I think it is pretty easy to add one. Just need the shape function and the DOF locations.

About the efficiency, is there any paper or presentation talking about the efficiency? Or is there any people compare the efficiency of solver based on libmesh or other lib like deal.ii etc? It is really a big issue which should be considered before people decided to put a lot of effort on a lib. Thanks a lot.

Sincerely Yours,

Lei Shi

On Mon, Aug 27, 2012 at 9:33 AM, Roy Stogner <> wrote:

On Mon, 27 Aug 2012, Lei Shi wrote:

I'm pretty new to this project. thanks for your fabulous job. I want
to implement a hp-adaptive dg solver based on libmesh. So I read
that famous paper, libMesh: A C++ Library for Parallel Adaptive Mesh
Refinement/Coarsening Simulations. However, it mentioned that the
p-adaptation will be support in the future. I know it is kind of
outdated. So does libmesh support p-adaptation now? 

Yes, but in a couple critical functions (constraint equation
generation, solution projection) we only support p-adaptivity using
hierarchic bases, where the set for every degree p is a subset of the
set for p+1.

IIRC that describes all of our discontinous element types, though, so
it shouldn't be an issue using DG.

There may still be a bug in some of our hp constraint equation code in
a couple corner cases.  However if you're doing DG there's no
constraint equations and again the concern won't apply.

P.S. How about the test coverage of the code? I found out the test
project is kind of old and the lasted committing is several years
ago. Does libmesh have unit test or regression test?  Thanks a lot.

Our unit testing is deplorable - the unit test suite gets
automatically run every several hours, but as you noticed the tests
are quite old and the test coverage is very incomplete.  If anyone has
enough free time or gets bored enough to contribute to these, it would
be highly appreciated.

Our regression testing is a little better - the examples in libMesh
itself aren't rigorous enough as regression tests (they effectively
just catch logic failures using library internal assertions and gross
accuracy failures via manual examination), but both UT-Austin and INL
have a few suites of libMesh application tests that get run regularly
with varying configurations and parameter settings and get tested via
automatic solution comparison.

I say only "a little better" because there are still gaps in the
feature coverage - I don't think we've got anything that hits
p-adaptivity, in particular.