Services & ResourcesWolfram ForumsMathGroup Archive

[Date Index] [Thread Index] [Author Index]

Re: Re: Simplification to Partial Fractions

• To: mathgroup at smc.vnet.net
• Subject: [mg59742] Re: [mg59699] Re: [mg59676] Simplification to Partial Fractions
• From: stephen layland <layland at wolfram.com>
• Date: Fri, 19 Aug 2005 04:32:20 -0400 (EDT)
• References: <200508180416.AAA08527@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

and thus spake Jon Palmer [2005.08.18 @ 00:21]:
> At first glance I can't make PolynomialReduce do what I need.
> 
> Here is an example problem. Take the expression:
> 
> u1 = A + (B*(x^2 - y^2)^2)/(x^2 + y^2) +  (C*(y^2 - z^2)^2)/(y^2 + z^2)
>  + (D*(-x^2 + z^2)^2)/(x^2 + z^2) 
> 
> Now 
> 
> u2 = Factor[u1]
> 
> 
> 
> How do you Simplify u2 back to the form of u1? 

Here's a hacky way to do it:

  close = Collect[Simplify[Apart[u2]], {(x^2 + y^2)}]

  Simplify[close /. A + (B*(x^2 - y^2)^2)/(x^2 + y^2) -> q] /. 
    q -> A + (B*(x^2 - y^2)^2)/(x^2 + y^2)

--
/*------------------------------*\
|        stephen layland         |
|    Documentation Programmer    |
| http://members.wri.com/layland |
\*------------------------------*/

• References:
  • Re: Simplification to Partial Fractions
    • From: "Jon Palmer" <jonathan.palmer@new.oxford.ac.uk>