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Re: Integration variables

• To: mathgroup at smc.vnet.net
• Subject: [mg78348] Re: Integration variables
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Thu, 28 Jun 2007 06:35:34 -0400 (EDT)
• Organization: Uni Leipzig
• References: <f5vr6e$j12$1@smc.vnet.net>
• Reply-to: kuska at informatik.uni-leipzig.de

Hi,

you have to write out

d Cos[th]

as

-Sin[th] d th

Regards
   Jens

mattew wrote:
> Hi everybody, Mathematica gives us the possibility to use spherical coordinates (r,Ttheta,Pphi): I'm trying to write an integral in the polar angle Ttheta of the form:
> 
> Integral in [-1,1] Ttheta dCos(Ttheta)
> 
> where Ttheta is the polar angle and the integration variable is the cosine of Ttheta in the interval [-1,1].
> 
> I got the following error:
> 
> ntegrate::ivar: "Cos[Ttheta] is not a valid variable."
> 
> Does anyone knows the reason for that?
> 
> p.s: It happens with any system of coordinates, actually.
>