Visualisation of the first 4 terms of the Fourier series of a square wave Join the Simple Science and Interesting Things Community and share interesting stuff! https://plus.google.com/communities/117518490246975838002 In mathematics, a Fourier series (English pronunciation: /ˈfɔərieɪ/) is a way to represent a wave-like function as a combination of simple sine waves. More formally, it decomposes any periodic function or periodic signal into the sum of a (possibly infinite) set of simple oscillating functions, namely sines and cosines (or complex exponentials) http://en.wikipedia.org/wiki/Fourier_series http://en.wikipedia.org/wiki/File:Fourier_series_square_wave_circles_animation.gif