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Re: Mathematica's FactorialSimplify command

• To: mathgroup at smc.vnet.net
• Subject: [mg8553] Re: Mathematica's FactorialSimplify command
• From: Paul Abbott <paul at physics.uwa.edu.au>
• Date: Sat, 6 Sep 1997 23:16:19 -0400
• Organization: University of Western Australia
• Sender: owner-wri-mathgroup at wolfram.com

Amy Calhoun wrote:

> I am trying to figure out how to use a Mathematica package that contains the
> command FactorialSimplify.  

I assume then that this a version 2.2 package.  The functionality of
FactorialSimplify has been absorbed into FullSimplify (or you can use
FunctionExpand):

	In[1]:= FunctionExpand[(n + 1)!/(n - 3)!]
	Out[1]= (n - 2) (n - 1) n (n + 1)

	In[2]:= FullSimplify[(n + 1)!/(n - 3)!]
	Out[2]= (n - 2) (n - 1) n (n + 1)

	In[3]:= FunctionExpand[Gamma[n + 2]/(n - 3)!]
	Out[3]= (n - 2) (n - 1) n (n + 1)

	In[4]:= FullSimplify[Gamma[n + 2]/(n - 3)!]
	Out[4]= (n - 2) (n - 1) n (n + 1)

In 3.0, if you replace all occurences of FactorialSimplify by
FunctionExpand it should work.

> In the book "A=B" there are several  references to
> a Mathematica command called FactorialSimplify.  The book says that the command
> can be found in the package DiscreteMath`RSolve`.  I've loaded this package and
> I've not found the command, and the help command just returns that
> FactorialSimplify is a global variable.  

You have probably already "referred" to FactorialSimplify (by entering
it before loading the package DiscreteMath`RSolve`).  If you 

To stick with the 2.2 you should load

	Needs["DiscreteMath`RSolve`"]

before you call FactorialSimplify.

Cheers,
	Paul 

____________________________________________________________________ 
Paul Abbott                                   Phone: +61-8-9380-2734
Department of Physics                           Fax: +61-8-9380-1014
The University of Western Australia           
Nedlands WA  6907                     mailto:paul at physics.uwa.edu.au 
AUSTRALIA                              http://www.pd.uwa.edu.au/Paul

            God IS a weakly left-handed dice player
____________________________________________________________________