I'm a mathematician and most of my answers here reflect the fact that I primarily program with Mathematica. In years past, I programmed a fair amount in C and Java and have dabbled a bit in Python more recently.
Q&A for users of Mathematica
Q&A for people studying math at any level and professionals in related fields
Q&A for professional and enthusiast programmers
Q&A for professional mathematicians
Stack Exchange Network staging zone, where users come together to build new Q&A sites
Q&A for apps, scripts, and development with the Stack Exchange API
Q&A for users of TeX, LaTeX, ConTeXt, and related typesetting systems