You see a curve describing a periodical function f with
period 2 .
Your task is to find the first terms of the
Fourier series development
of this function.

You can make several attempts to find these terms.
For each attempt you will see the
curve of your "development" g together with f. You can modify
your answer to make the curves as similar as possible.
There is also the curve of remainder f-g, which allows you to
see the errors.