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MathGroup Archive 2005

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Re: Trouble with an integral

  • To: mathgroup at smc.vnet.net
  • Subject: [mg57403] Re: Trouble with an integral
  • From: dh <dh at metrohm.ch>
  • Date: Fri, 27 May 2005 04:56:40 -0400 (EDT)
  • References: <d741q1$iff$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi Valeri,
If you write the integrand in the form:
Exp[-a x] ... rest containing no a
it is clear that the integral should become smaller the larger a.
We definitively have a bug here that Wolfram should take notice of.

I beg Daniel Lichtblau to send a notice to the corresponding person.
Sincerely, Daniel

Valeri Astanoff wrote:
> Bonjour le groupe,
> 
> Could someone give me the right answer
> for this integral with parameter 'a' ?
> 
> In[1]:=$Version
> 
> Out[1]=5.0 for Microsoft Windows (November 18, 2003)
> 
> In[2]:=Integrate[Sqrt[1+Sqrt[x]]/(2*Sqrt[2]*E^(a*x)*Sqrt[x]),{x,0,1},
>   Assumptions -> a>0]
> 
> Out[2]=(1/3)*(4 - Sqrt[2])
> 
> In[3]:=%//N
> 
> Out[3]=0.861929
> 
> In[4]:=NIntegrate[Sqrt[1+Sqrt[x]]/(2*Sqrt[2]*E^(2*x)*Sqrt[x]),{x,0,1}]
> 
> Out[4]=0.491465
> 
> 
> 
> Thanks in advance.
> 
> v.a.
> 


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