Re: Integrate Bug
- To: mathgroup at smc.vnet.net
- Subject: [mg100029] Re: Integrate Bug
- From: Erik Max Francis <max at alcyone.com>
- Date: Fri, 22 May 2009 01:44:18 -0400 (EDT)
- References: <gv2jh5$97b$1@smc.vnet.net>
Ney Lemke wrote:
> I am trying to calculate this integral that should be positive.But the
> answer is 0.
>
> In: Integrate[(1)/(z^2 + b^2 + a^2 - 2 z b Sin[\[Theta]] -
> 2 a b Cos[\[Theta]])^(1/2), {\[Theta], 0, 2 \[Pi]},
> Assumptions -> {a > 0, b > 0, z > 0}]
>
> Out:0
>
> Anybody have notice a situation like that?
>
> My platform is MacOSX 10.4 and Mathematica 7.
I can confirm that I also get 0 (Mathematica 7.0.1 on CentOS).
Numerical integrations demonstrate that the result definitely is not
generally zero for arbitrary positive a, b, and z. Looks like a bug to me.
--
Erik Max Francis && max at alcyone.com && http://www.alcyone.com/max/
San Jose, CA, USA && 37 18 N 121 57 W && AIM, Y!M, Skype erikmaxfrancis
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