Both the documentation at http://docs.python.org/lib/module-random.html and the docstring have the same erroneous input conditions. They claim input must be >-1 when it must in fact be >0.

Note also the freak "}" that has snuck into the docstring (copied and pasted from the documentation perhaps?).

>>> import random
>>> print random.betavariate.__doc__
Beta distribution.

        Conditions on the parameters are alpha > -1 and beta} > -1.
        Returned values range between 0 and 1.


>>> random.betavariate(0, 0)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/lib/python2.3/random.py", line 594, in betavariate
    y = self.gammavariate(alpha, 1.)
  File "/usr/lib/python2.3/random.py", line 457, in gammavariate
    raise ValueError, 'gammavariate: alpha and beta must be > 0.0'
ValueError: gammavariate: alpha and beta must be > 0.0

This seems to be a duplicate of 1635892