# Beautiful Mathematics in All Browsers

I recently discovered the wonderful MathJax. MathJax is a JavaScript library that displays mathematical formulas in web pages. It's very easy to set up and it renders beautiful mathematics.

For example:

*
Suppose \( U \) is an open subset of the complex plane
\( \mathbb{C} \),
\( f : U \rightarrow \mathbb{C} \) a holomorphic function,
and the closed disk \( D = \{z : |z - z_0| \leq r\} \)
is completely contained in \( U \).
Let \( \gamma \) be the circle
forming the boundary of \( D \).
Then for every a in the interior of \( D \):
*
$$
f(a) = \frac{1}{2 \pi i}
\oint_{\gamma}{ \frac{f(z)}{z-a} dz}
$$
*
where the contour integral is taken counter-clockwise.
*

That is, of course, Cauchy's integral formula.