SymPy is great. I've used it and read through the code (available open source). ...

		jrpickhardt on Sept 1, 2012 \| parent \| context \| favorite \| on: SymPy - Python library for symbolic mathematics SymPy is great. I've used it and read through the code (available open source). Also, my online calculator Encalc.com uses SymPy on the backend. For example: http://www.encalc.com/#expr=integrate(sin(x))

Looks like the link cut off the closing parentheses.