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MathGroup Archive 2002

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Re: Problem: Integrate

  • To: mathgroup at smc.vnet.net
  • Subject: [mg33609] Re: [mg33589] Problem: Integrate
  • From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
  • Date: Wed, 3 Apr 2002 18:08:12 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

It is a bug and  a rather curious one, considering that:

In[1]:=
Integrate[ -1 + Cos[\[Theta]]^2 + Sin[\[Theta]]^2,{\[Theta], 0,a}]

Out[1]=
0

You will get the answer ComplexInfinity whenever one of the limits is an 
integer multiple of Pi, e.g.

In[3]:=
Integrate[ -1 + Cos[\[Theta]]^2 + Sin[\[Theta]]^2,{\[Theta], 0,3Pi}]

Out[3]=
ComplexInfinity

  but

In[4]:=
Integrate[ -1 + Cos[\[Theta]]^2 + Sin[\[Theta]]^2,{\[Theta], 0,3Pi/2}]

Out[4]=
0



Andrzej Kozlowski
Toyama International University
JAPAN
http://platon.c.u-tokyo.ac.jp/andrzej/


On Wednesday, April 3, 2002, at 03:13  PM, Alexander Baehr wrote:

>
> Hello everybody,
>
> for
> Integrate[ -1 + Cos[\[Theta]]\^2 + Sin[\[Theta]]\^2,
> \ {\[Theta], 0, 2 \[Pi]}]
>
> I get the result
>
> ComplexInfinity
>
> though the result is obviously zero. The Calculation is OK if I remove
> one of the three terms, such that the result is no longer zero.
>
> Is this a bug?
>
> Thanks
> Alexander
>
>
>
>
>
>



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