Applied Mathematics/Fourier Cosine Series

Fourier cosine series

The series below is called Fourier cosine series.

$f(x)=\frac{a_0}{2}+\sum _{n=1}^{\mathrm{\infty }}{a}_n\cos \frac{n\pi x}{L}$

where

$a_n=\frac{2}{L}\underset{0}{\overset{L}{\int }}f(x)\cos \frac{n\pi x}{L}dx$