Will Pazner

Do you have an example mesh that you can share? MFEM treats periodic meshes by "collapsing" the periodic vertices into a single vertex. You can get the degrees of freedom...

In your example mesh, the non-periodic boundaries have boundary attributes 1 and 5. You can get the associated DOFs by calling `FiniteElementSpace::GetEssentialTrueDofs`, for example: ```cpp Array bdr_is_ess(6); bdr_is_ess = 0;...

Hmm, it looks like the face Jacobian matrices are not actually computed in the face geometric factors (thanks for reporting this). I suppose this was never implemented — is that...

The Jacobian in this case will be 3x2 (more generally, $\mathrm{sdim} \times \mathrm{dim}$). If you want to solve a diffusion problem on a 2D surface in 3D, you should add...

Are you considering specifically the curl-free subspace of H(curl)? In which case the mass matrix coincides with the diffusion operator. But yes, I agree that the H(curl) mass integrator on...

@YohannDudouit, @v-dobrev, @camierjs any thoughts on computing the Jacobian matrices in the face geometric factors? Is this planned? Should we just error out with a message for now?

@jandrej, could I suggest a couple small changes that I noticed in the DFEM code? Return unique pointer instead of shared You can always assign the unique_ptr to a shared_ptr...

> I'll address those in a separate PR. @jandrej, is there a PR for these?

I think this is a good change 👍 Things like this are good candidates for automated static analysis tools like clang-tidy. It has a specific check (`modernize-use-override`) that checks exactly...

Looks like a correct fix to me. Do you want to make a PR?