Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2003
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2003

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

Search the Archive

Re: Integration of Exp[-x^2]/(1 + Exp[a * x])

  • To: mathgroup at smc.vnet.net
  • Subject: [mg39635] Re: Integration of Exp[-x^2]/(1 + Exp[a * x])
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Thu, 27 Feb 2003 00:27:15 -0500 (EST)
  • Organization: Universitaet Leipzig
  • References: <b3hs7u$iki$1@smc.vnet.net>
  • Reply-to: kuska at informatik.uni-leipzig.de
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

if Exp[a*x] < 1 you can try a geometric series, i.e.,

1/(1+Exp[a*x})= Sum[(-Exp[a*x])^n,{n,0,Infinity}]

and integrate

term=Integrate[Exp[-x^2]*(-Exp[a*x])^n, x]

and work with

Sum[Evaluate[term], {n, 0, Infinity}]

for a<0 the sum should be quickly convergent.

Regards
  Jens

Stefan wrote:
> 
> Hello,
> 
> I have to integrate the function Exp[-x^2]/(1 + Exp[a * x]) where a is
> real-valued parameter. Unfortunately
> 
> Integrate[Exp[-x^2]/(1 + Exp[a * x]), x]
> 
> yields no results. Does anyone know a clever trick I might have missed? Any
> hint would be welcome,
> 
> Thanks in advance, Stefan


  • Prev by Date: Re: Cursors in graphics
  • Next by Date: Re: Domain of Sin[ArcSin[x]] ?
  • Previous by thread: Re: Re: Integration of Exp[-x^2]/(1 + Exp[a * x])
  • Next by thread: Re: Integration of Exp[-x^2]/(1 + Exp[a * x])