From: Warren Brown <wkb@...>
Date: 2003-09-17T06:16:21+09:00
Subject: Re: performance and style advice requested

Hal,

> Unfortunately, I can't remember exactly how
> it works.
>
> There are formulae that involve (n-k)!,
> perhaps in the denominator, I can't recall.
> And in the degenerate case where n=k,
> "common sense" tells us that we get the
> right answer if 0! is arbitrarily defined
> to be 1. So we do that.

    Pretty much any way you define the factorial function, you always end up
with some form of the relationship:

X! = X * (X - 1)!

    Or, put another way:

(X - 1)! = X! / X

    So, for X == 1:

0! = 1! / 1

    - Warren Brown