On May 1, 5:21 pm, "Jordan Harry" <[EMAIL PROTECTED]> wrote: > I'm trying to write a simple program to calculate permutations. I created a > file called "mod.py" and put the following in it: > > def factorial(n): > a = n > b = n > while a>0 and b>1: > n = (n)*(b-1) > b = b-1 > > def perm(n, r): > a = factorial(n) > b = factorial(n-r) > q = a / b > print q > > Then I went back to IDLE and input the following: > > >>> import mod > >>> mod.perm(5, 4) > > I recieved the following error message: > > Traceback (most recent call last): > File "<pyshell#1>", line 1, in <module> > mod.perm(5, 4) > File "C:\Python25\mod.py", line 27, in perm > q = a / b > TypeError: unsupported operand type(s) for /: 'NoneType' and 'NoneType' > > I have no idea how to fix it. I'm pretty new to Python. I have IDLE 1.2.2 > and Python 2.5.2, > > Please help.
Your factorial function needs to return something. ~Sean -- http://mail.python.org/mailman/listinfo/python-list
