NameError function not found

[Cameron Pulsford]

Hey everyone, I am extremely stumped on this. I have 2 functions..

def _determinant(m):
   return m[0][0] * m[1][1] - m[1][0] * m[0][1]

def cofactor(self):
   """Returns the cofactor of a matrix."""
   newmatrix = []
   for i, minor in enumerate(self.minors()):
       newmatrix.append(_determinant(minor.matrix) * ((i%2) * -1))
   return newmatrix

And I get the following error when I try to run a.cofactor()...

"NameError: global name '_determinant' is not defined"

When I put the _determinant function nested within the cofactor function it
works fine. Normally I would do this, but a lot of other methods use the
_determinant method. They are both in the same class, and they are at the
same level, they are even in that order so I know it should be  able to see
it. I have a lot of functions that call other functions in this class and
everything is fine. [Also for the picky, I know my cofactor method isn't
mathematically correct yet ;-) ] Am I missing something obvious here? Also
if it helps the rest of the code is here
http://github.com/dlocpuwons/pymath/blob/d1997329e4473f8f6b5c7f11635dbd719d4a14fa/matrix.py
though
it is not the latest.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-list/attachments/20090529/f8ab9b12/attachment.html>