a repository of mathematical know-how

Plenty of LaTeX errors

Plenty of LaTeX errors

Creating a new article I kept getting LaTeX errors like this:

LaTeX processing error: math_failure (math_unknown_error):\frac{p}{q}

I left one error in the article I was making: Finding an interval for rational numbers with a high denominator I also found it impossible to typeset a piecewise function definition without getting a LaTeX error, I tried using two different ways, using \begin{array} and the \begin{cases} but neither worked. I searched around hoping to find a piecewise defined function in some other article, but found nothing. Is it feasible to try to typeset reasonably complex equations like this on the Tricki? The formatting guidelines didn't really get into complex typesetting, and applying normal LaTeX code doesn't really work.

I found this site only recently and I've found it immensely helpful; it seems to be exactly what I've been hoping to find on the internet for a while, but I'm not sure to what extent it is still active. I'd love to contribute what I can though!