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## #1 2012-10-24 14:46:44

Kenjiska
Guest

### Factorial

Please,tell me the value of these-
i !
(-1) !
(1+i) !
(.1) !

## #2 2012-10-24 16:45:29

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 107,146

### Re: Factorial

Hi;

(-1) ! does not exist. All the negative integers of the factorial function are equal to infinity.

I would use a Taylor series for some of them. How much accuracy do you need.

Basically though you would use a computer or Wolfram Alpha to look those up. If your teacher wants to see some method then how is it you do not know that method? If I use series expansion he/she may not want that method used. So provide me with what method is to be used.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #3 2012-10-24 20:19:34

Kenjiska
Guest

### Re: Factorial

Show me using the taylor series

## #4 2012-10-24 21:43:25

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 107,146

### Re: Factorial

Hi;

Those are all difficult but here goes nothing!

Let's try (.1)! first. For that we use a series and a trick.

It is in nested or Horner form for fast computation. The series is best for values >=5 so we put in z = 5.1

We take the exponential of both sides and get.

Now to get .1! we use a simple relation:

So

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Online

Kenjiska
Guest

(1+i)!
i !

## #6 2012-10-24 23:41:49

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 107,146

### Re: Factorial

For i! use this truncated series:

Substituting z = i you get

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Online

## #7 2012-10-25 04:25:29

zetafunc.
Guest

### Re: Factorial

Also, for (1+i)!, you can find that using bobbym's answer, since