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
>
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>
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>
>

```

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