Hello,

Using Parseval's Theorem:

$\displaystyle \int_a^b f(x)^2 dx = 2\pi (\frac{a_0}{2})^2 + \sum_{n=1}^{\infty}[ a_{n}^2\pi + b_{n}^2\pi ] $

I know that a,b are usually $\displaystyle 0,2\pi $ or $\displaystyle -\pi,\pi $, how does one determine their values?