Modular arithmetic is probably one of the coolest subjects we covered in high school, but we didn't spend enough time on it. I actually learned all about it from reading Simon Singh's <i>The Code Book</i> in sixth grade--it's a great introduction to cryptography and covers the basics of modular arithmetic to introduce RSA.<p>Towards the end of high school, I decided to play around with graphing equations as colors. I came up with a bunch of cool patterns including pretty much all of the ones in the article--the easiest way to make a function well-behaved across a color channel is to make it mod 255. Playing around with different functions this way is really fun; I suggest everybody try it.<p>If you want to draw pictures like this but don't want to write your own program for this, you can use mine: <a href="http://inst.eecs.berkeley.edu/~tikhon/draw" rel="nofollow">http://inst.eecs.berkeley.edu/~tikhon/draw</a>.
Looks like the stuff I like to play with:<p><a href="http://alquerubim.blogspot.com/2010/07/o-vendedor-de-tapetes.html" rel="nofollow">http://alquerubim.blogspot.com/2010/07/o-vendedor-de-tapetes...</a><p><a href="http://alquerubim.blogspot.com/2010/07/visoes-do-camelo.html" rel="nofollow">http://alquerubim.blogspot.com/2010/07/visoes-do-camelo.html</a>
Pretty cool. I always thought fractals looked like Cthulhu. Also the part where Cthulhu is said to be a cosmic entity and bring subconscious anxiety to humans. Reminds me of fractals in math class.