Reference: http://freedomuniversity.ning.com. This shows how a square wave is represented by a series of sine waves including the fundamental and its harmonics. How you weigh the importance of each sine wave is governed by calculating the Fourier Coefficients of a square wave. The calculation is shown in another video. Other related topics include: fft, fast fourier transform, fourier transform, discrete cosine transform, These video topics will be produced by Professor John Santiago and you can contact him at john@e-liteworks.com