[jamessb]

This is a nice introduction, but it looks there is a problem with the formatting: some of the math is not rendered properly (in the source, some expressions are wrapped in dollar-signs rather than script tags).

[aria]

What browser are you in? It just using MathJax and appears to work in WebKit and Firefox.

[jamessb]

Firefox 33.1.1 on Mac OS 10.10.1. Initially it would get stuck looking like: http://imgur.com/DhXAmI7

After refreshing the page a few times, all the formulae rendered correctly. In Safari things rendered correctly immediately.