possible cythonization

[nucccc]

#29 ,as per the pull request, I note here some thoughts about cythonization.

By just declaring with cdef the integers i and j in the for loops it would be possible to improve a speed-up with a very limited code modification. Still that would require a cythonization (a .pyx file, importing cython, transpilation build and then importing the eventual .so extension... i suppose).

I leave it here as a side note, knowing that a quick benchmark allowed to have a 30% performance speedup in a benchmark I recall I made. I suppose the code already leverages at best numpy.

[cjekel]

I need to respond to #29 (comment)

Curious what happens to the cythonization if everything is written in cython, even the distance functions.

[nucccc]

If you're interested I could open a branch (also in a fork of mine) with some cythonized code in dedicated folder, for intermediate evaluations. Hopefully I could do that in the upcoming week if I find the time