https://github.com/AnykeyNL/Quincy/blob/master/coordcalc.py#...

There is a loop in a loop that goes through all the possible values of x and y to find the correct ones. No wonder it's so slow!

The scipy solver - inspired by the original article, I used https://docs.scipy.org/doc/scipy/reference/generated/scipy.o... - isn't much faster though (from reading the docs, it's just a smarter random search).

I guess it's time to learn some linear algebra (again!) and create a custom algorithm.