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MathGroup Archive 2007

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Re: Solving a Integral

  • To: mathgroup at smc.vnet.net
  • Subject: [mg78063] Re: Solving a Integral
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
  • Date: Fri, 22 Jun 2007 06:36:44 -0400 (EDT)
  • Organization: The Open University, Milton Keynes, UK
  • References: <f5dkds$no$1@smc.vnet.net>

ehrnsperger.b at pg.com wrote:
> I need help in solving the following integral:
> 
> Integral = 1/(beta^alpha* Gamma[alpha]) *
> Integrate[x^(alpha-1)*Exp[-x/beta]/(1+Exp[-a*x-b]),{x,0, infinity},
-----------------------------------------------------------^^^^^^^^
oo Must be written Infinity (with a capital I)

> Assumptions: (alpha> 0)||(beta > 0)||(a > 0)||(b <0)]
-------------^^
The : character means nothing here: use ->

Moreover, are you sure that you want a OR ( that is ||) condition on 
your assumptions rather than an AND (that is &&)?

HTH,
Jean-Marc

> The Integral is approximately 1/(beta^alpha* Gamma[alpha])
> *1/(1+Exp[-a*alpha*beta-b]) + Order[alpha*beta^2]
> 
> However, I would like to have an exact analytical solution, and I am
> failing to convince Mathematica to give me the solution. Is there a way to 
> ask Mathematica to give the solution as a series expansion of my
> approximate solution?
> 
> Thanks so much for your help,
> 
> Bruno
> 
> Dr. Bruno Ehrnsperger
> Principal Scientist
> 
> Procter & Gamble Service GmbH
> Sulzbacherstr.40
> 65824 Schwalbach
> Germany
> 
> fon +49-6196-89-4412
> fax +49-6196-89-22965
> e-mail: ehrnsperger.b at pg.com
> internet: www.pg.com
> 
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> Willi Schwerdtle
> Sitz: Sulzbacher Str. 40, 65824 Schwalbach am Taunus, Amtsgericht:
> K=F6nigstein im Taunus HRB 4990
> 
> 



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