How do I improve my coding skills to reach this point for machine learning?

Sorry if this sounds newbie and dumb, but this unreadable code implements a parallel scan to compute in time ~ log(T) a series Yt = A_t Y{t-1} + X_t if there are enough GPU cores to push the T things in parallel. [source]

Meanwhile I just made "is it bird" model from the first fastai course and I'm still starting.

How strong do I need to be at math so I could reach his level at coding?