a = b not equivalent to a = ab

Fri Aug 26 02:20:17 EDT 2016

I've been playing with the binomial function, and found that in the below code, rs *= x does not behave the same way as rs = rs * x. When I set FAIL to True, I get a different result. Both results are below.
I had read that the two were equivalent. What am I missing?
thanks,
 -= miles =-
#!/usr/bin/python2
import sys
FAIL= True if len(sys.argv)>1 else False
def bin(n,k):
 rs=1
 k=min(k,n-k)
 
 for i in range(1,k+1):
 if FAIL: rs *= (n-(i-1))/i # these should be the same, 
 else: rs = rs * (n-(i-1))/i # but apparently are not
 return rs
 
 
for n in range(10):
 for k in range(n+1):
 print bin(n,k),
 print''
 
------------------- output -------------------------
$ pascal2
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
1 6 15 20 15 6 1
1 7 21 35 35 21 7 1
1 8 28 56 70 56 28 8 1
1 9 36 84 126 126 84 36 9 1
$ pascal2 fail
1
1 1
1 2 1
1 3 3 1
1 4 4 4 1
1 5 10 10 5 1
1 6 12 12 12 6 1
1 7 21 21 21 21 7 1
1 8 24 48 48 48 24 8 1
1 9 36 72 72 72 72 36 9 1

a *= b not equivalent to a = a*b

a = b not equivalent to a = ab