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Re: How to simplify to a result that is real

• To: mathgroup at smc.vnet.net
• Subject: [mg50725] Re: How to simplify to a result that is real
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Sat, 18 Sep 2004 05:48:16 -0400 (EDT)
• Organization: Universitaet Leipzig
• References: <cidt38$brv$1@smc.vnet.net>
• Reply-to: kuska at informatik.uni-leipzig.de
• Sender: owner-wri-mathgroup at wolfram.com

Hi,

my Mathematica 5.0.1 say

(-2*ArcTan[((-1 + e)*Tan[a/2])/Sqrt[1 - e^2]])/
 Sqrt[1 - e^2]

and it looks real ?

Regards
  Jens

Richard Chen wrote:
> 
> The command:
> 
> Integrate[1/(1 + e Cos[t]), {t, 0, a},
>   Assumptions -> {-1 < e < 1, 0 < a < Pi}]
> 
> leads to a complex valued result. I could not make
> mathematica to render the result in a form that is
> purely real. ComplexExpand, Refine all do not seem to work.
> 
> Does anyone know how to make mathematica to simplify this
> result into a real form?
> 
> Thanks for any info.
> 
> Richard

• Follow-Ups:
  • Re: Re: How to simplify to a result that is real
    • From: DrBob <drbob@bigfoot.com>