Re: Solving a Integral

*To*: mathgroup at smc.vnet.net*Subject*: [mg78125] Re: Solving a Integral*From*: dimitris <dimmechan at yahoo.com>*Date*: Sat, 23 Jun 2007 07:14:20 -0400 (EDT)*References*: <f5dkds$no$1@smc.vnet.net>

I think tour integral does not have a closed form solution (at least using Mathematica for evaluating!). Did you search some of the well known collections of integral tables? Dimitris ehrnsperge... at pg.com : > 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}, > Assumptions: (alpha> 0)||(beta > 0)||(a > 0)||(b <0)] > > 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 > > Gesch=E4ftsf=FChrer: Otmar W. Debald, Gerhard Ritter, Dr. Klaus Schumann, > Willi Schwerdtle > Sitz: Sulzbacher Str. 40, 65824 Schwalbach am Taunus, Amtsgericht: > K=F6nigstein im Taunus HRB 4990