Whenever I try to use any of the built-in functions of Python's exponentiation and logarithms module, I get an error like this:

NameError: name 'sqrt' is not defined

I have tried using math.sqrt(4), sqrt(4) and sqrt(4.0), but none of them works. The exception is pow, which works as it's supposed to. This is really strange and I'm not sure what's wrong.