Peter Hill

Ok, I can make `XZHermiteSpline` a base class of `XZPetscHermiteSpline` too to avoid the duplication of the basis calculations. We could also add `XZPetscMonotonicHermiteSpline` by simply doing the interpolation and...

I worked out why I was getting different warnings in CI than locally -- `fmt` was turning off that warning, but a bug meant they didn't restore the previous settings....

Hmm, `FV::Div_par_fvv` MMS fails for FCI, it gets order ~1.3, but there is a comment on the penalty term: ```cpp // Penalty terms. This implementation is very dissipative. ``` in...

I've tried [this version of the penalty term for `Div_par_fvv`](https://github.com/boutproject/hermes-3/commit/770d09e464c29b037acbc8d9df85413dc93e6192) as suggested by @dschwoerer, but it has the same behaviour as the version here. Does anyone have a derivation of...

I think the conclusion of `FV::Div_par_fvv` is that it's just a first order operator, at least for general oscillatory inputs