Is there factorials of negative numbers?

Syth

I've been thinking quite recently about maths :-D and I've been wondering about factorials. Firstly, here's a definition of a factorial:
n! = n(n-1)! and 1!=1, by definition.
BTW it's easy to see why 0!=1 as 1! = 1*0! = 1 (by def) =>0!=1.

So what about negative numbers? Would you need a new definition of factorials or what? Is ther such things as the factorials of negative numbers?

ecksor

Doesn't appear to be defined for negative integers.

http://mathworld.wolfram.com/Factorial.html

mirv

How would you go about using a negative factorial anyhow? You can't really say that theres -6 positions to occupy a (-3)! or anything!

Mr. Flibble

According to my calculator, no.

Stark

Factorials of negative numbers are undefined.

However there is an integral which is sometimes used to approximate factorials without actually going by the definition and you can get the results for negative numbers from this. However the result isn't a real factorial.

Capt'n Midnight

If you re-define a factorial of a number as being the product of all the integers between itself and zero (excluding zero of course) then the magnitude will be the same as the positve equlivant and only half of the would be negative...

Maybe there are things that are fractional factorials eg: instead of N! you could have N!m where m is number of fratiion that can divide into m

eg: 5!4 would be 1/4 * 1/2 * 3/4 .... * 4 1/2 * 4 3/4 * 5..

But it would work out as (n.m)! / n.m
so again not really interesting

Man U babe

try this
The function given in this takes on the values of the factorial function for all positive whole numbers, its negative values are as close as I reckon you could get to an answer for factorials of negative numbers.
<gaaah>I'm contemplating maths during my summer holidays</gaaah>