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Re: Integrate without Simplify

• To: mathgroup at smc.vnet.net
• Subject: [mg43949] Re: Integrate without Simplify
• From: Paul Abbott <paul at physics.uwa.edu.au>
• Date: Wed, 15 Oct 2003 04:59:25 -0400 (EDT)
• Organization: The University of Western Australia
• References: <bl0urk$405$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

In article <bl0urk$405$1 at smc.vnet.net>, k.junk at verizon.net (Kevin VW) 
wrote:

> I have about 10000 term in a list that I want to integrate. 

Let me guess -- each term is of certain form? And can this particular 
form be integrated in a generic fashion? If so, then you can, and 
should, use pattern-matching to perform the integral. For example, if 
you have 10000 terms of the form

   x^n Exp[-a x]

with different n and a, and you need to compute the integral with 
respect to x over [0,Infinity). The generic integral is then

  n! / a^(n+1)

and the 10000 term list can be integrated by pattern-matching

  longlist /. x^(n_) Exp[a_ x] :> n! / (-a)^(n+1)

Cheers,
Paul

-- 
Paul Abbott                                   Phone: +61 8 9380 2734
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