theadana and pals, which I regret.Interleaving it with fiddling around with that O'Caml demo that Nels wrote. I found it surprisingly easy to turn that idea I had last October about "count-unbiased" averages into a little interactive toy. Props to O'Caml's Graphics library; it exposes some convenient things, and is (unlike other libraries/tools that expose nice interfaces for visualization such as Flash, Javascript+DOM, Processing) part of a sane language, but for which I would have probably gotten kind of annoyed in the middle of implementing Gaussian elimination.
(as for O'Caml, I find I actually do rather like the let-construct without "val"s everywhere and without an end. It sort of obviates tom7's "do" as found in humlock, since it's easy to just stick in imperative statements without any prefix.)
Screenshot:
Grab the source code here. To use, just unpack, run make, and run ./center