Unicode identifiers in Python?

Question

I want to build a Python function that calculates,

Answer 1

It's worth pointing out that Python 3 does support Unicode identifiers, but only allows letter or number like symbols (see http://docs.python.org/3.3/reference/lexical_analysis.html#identifiers for full details). That's why Σ works (remember that it's a Greek letter, not just a math symbol), but √ doesn't.