1 1. Add references and start citing them.
3 2. Profile (and fix?) any remaining slow operations.
5 3. When we take a Cartesian product involving a trivial algebra, we
6 could easily cache the identity and charpoly coefficients using
7 the nontrivial factor. On the other hand, it's nice that we can
8 test out some alternate code paths...
10 4. Can we hit "x" with the deortho matrix and delegate to the
11 _rational_algebra to speed up minimal_polynomial?