On Thu, May 13, 2010 at 5:31 PM, Mark Dickinson <report@bugs.python.org> wrote:
> And why are we trying to speed up the pure Python factorial code here?

I would expect that for large factorials the performance will be
determined by the number of long multiplications and the size of
multiplicands.

> I don't imagine that those speed differences are going to translate well to C.

The differences between recursive and non-recursive versions are not
likely to translate well, but the difference (if any) between the
order of multiplication most likely will.

In any case, I am attaching fixed version of factorial4.

$ ./python.exe -m timeit -s "from factorial4 import f0 as f" "f(10000)"
10 loops, best of 3: 65.5 msec per loop
$ ./python.exe -m timeit -s "from factorial4 import f1 as f" "f(10000)"
10 loops, best of 3: 66.9 msec per loop
$ ./python.exe -m timeit -s "from factorial4 import f2 as f" "f(10000)"
10 loops, best of 3: 56.5 msec per loop
$ ./python.exe -m timeit -s "from factorial4 import f3 as f" "f(10000)"
10 loops, best of 3: 63 msec per loop