# Friday Math Movie - Sine Wave to Square Wave using Fourier Series

By Murray Bourne, 14 Nov 2008

We learned about sine waves in elementary trigonometry:

The idea behind the **Fourier Series** is to add sine curves with different amplitudes and frequencies and the resulting curve can be either a square wave, a sawtooth wave or many other interesting periodic shapes. You can see more on this concept in this Introduction to Fourier Series.

This week's movie begins with a pure sine wave tone and then the other sine curves are added to it to produce something very close to a square wave (with the odd wiggle here and there) as the number of added curves becomes very large.

**Warning:** The final square wave tone may be pretty loud.

See the 3 Comments below.