We have enabled MathJax via the Discourse Math plugin. Now posts may include nicely formatted math expressions such as
f(x) = \int_{-y}^{y} \phi(y)sin(y) dy
The code for the expression above is as you would write an inline math expression in a LaTeX document:
$f(x) = \int_{-y}^{y} \phi(y)sin(y) dy$
Helpfully, the formatted math appears in the preview panel as you edit your post!
Most LaTeX math functions are support, at least the most common. For details, see MathJax TeX and LaTeX Support.
Enjoy!