Underling

Thirteen years ago, while working on the dissertation, I put together a 3D pencil transform library atop FFTW MPI called underling. It looked great in isolation. It never integrated correctly with my dissertation code. I eventually ran away because spending time on it wasn't time spend graduating

In the last couple of days I learned that there was no problem with the library from a correctness perspective. Instead, the mysterious problem was MKL exposes an incomplete FFTW implementation that simply returns NULL for a lot of methods. After some linking tinkering in my dissertation's primary codebase, my little pencil decomposition library snapped right into place.

This is both immensely satisfying (it worked after all!) and frustratingly painful (would have loved to benchmark/publish during the grad school days!). Alas.