Will Pazner

@YohannDudouit, could you take a look at this when you get a chance?

@smsolivier, sorry for the delay. This looks great! I will try to take a closer look at it soon, and review it more thoroughly.

@smsolivier, apologies for the long delay. I would like to make an effort to get this ready for review. I pushed some minor changes. Could you make whatever modifications are...

Here is an example of imposing boundary conditions for a saddle-point system. The key is to use `FormSystemMatrix` and `FormRectangularSystemMatrix` instead of calling `ParallelAssemble` and the various `Eliminate[…]` routines. ```c++...

Given an `OperatorHandle`, you can assess the underlying `Operator` with `operator*`, for example: ```c++ solver.SetOperator(*D); ``` (`OperatorHandle` is an object that behaves kind of like a pointer to an `Operator`,...

It looks roughly OK to me. Keep in mind you're just using a diagonal preconditioner for both blocks, which may be why you're getting so many iterations (if one of...

Here is a short [perl script](https://gist.github.com/pazner/c6773ad283f617501a5b4dc8d2fb421f) that tries to measure the size of commits in bytes. The idea is that it looks at the `diff-tree` for each commit, and then...

I tried working on a more generic way of doing this without introducing a lot of boilerplate, but I had trouble doing it. Maybe we need to introduce some macros...

> Lots of warnings from this branch: It was just because of something unrelated that got merged into master, see #2886. I just merged more recent master, hopefully it's fixed...

Keeping open for now, but this can be closed once #3066 is merged.