(doc) which scheme is chosen for which point

[Tigraan]

As the derivative of a given numpy array has the same size as the initial array, it could be worth mentioning how the differentiation switches between the backwards/forwards/centered scheme.

Looking at operators.diff() it uses "center" whenever it can apply it, "forward" at the left (low-index) boundary and "backward" at the right (high-index) boundary, but the source code is not that easy to read, and it is not written anywhere in the doc either.

[maroba]

That is correct. I will update the documentation accordingly.