How can I compute the Fourier series of a function on a interval using Wolfram ? For example, the Fourier of $f(x)=x^2$ on $[0,2\pi]$ prolonged on $\mathbb R$ by $2\pi$ periodicity. For example, if I put FourierSeries[x^2,x,n], Wolfram will give me back the fourier series on $[-1,1]$. I saw in the manual of Wolfram, but it's not written how to modify the interval. Any idea ?