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Re: Re: Incorrect symbolic improper integral

  • To: mathgroup at smc.vnet.net
  • Subject: [mg103668] Re: [mg103645] Re: [mg103586] Incorrect symbolic improper integral
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Fri, 2 Oct 2009 08:21:34 -0400 (EDT)
  • References: <30167826.1254225639354.JavaMail.root@n11> <200909300903.FAA09670@smc.vnet.net> <200910011038.GAA23569@smc.vnet.net>

Update their version? But that's the right answer...

Andrzej Kozlowski

On 1 Oct 2009, at 19:38, Curtis Osterhoudt wrote:

>  Yes, Jason is obviously using 7.0.0. I use that version on a linux  
> machine, and get what he reported. Wolfram|Alpha also gets Pi/E --  
> they need to update their version!
>
>
>> From: jwmerrill at gmail.com [mailto:jwmerrill at gmail.com]
>>
>>
>> Below is a definite integral that Mathematica does incorrectly.
>> Thought someone might like to know:
>>
>> In[62]:= Integrate[Cos[x]/(1 + x^2), {x, -\[Infinity], \[Infinity]}]
>>
>> Out[62]= \[Pi]/E
>>
>> What a pretty result--if it were true. The correct answer is \[Pi] 
>> *Cosh
>> [1], which can be checked by adding a new parameter inside the
>> argument of Cos and setting it to 1 at the end:
>>
>> In[61]:= Integrate[Cos[a x]/(1 + x^2), {x, -\[Infinity], \ 
>> [Infinity]},
>>  Assumptions -> a \[Element] Reals]
>>
>> Out[61]= \[Pi] Cosh[a]
>>
>> Regards,
>>
>> Jason Merrill
>>
>>
>>
>>
>
>
> -- 
> ==================================
> Curtis Osterhoudt
> cfo at remove_this.lanl.and_this.gov
> PGP Key ID: 0x4DCA2A10
> ==================================
>



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