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MathGroup Archive 2005

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Re: bugs in Mathematica 5.1

  • To: mathgroup at smc.vnet.net
  • Subject: [mg54051] Re: bugs in Mathematica 5.1
  • From: Arne Eide <arne at nfh.uit.no>
  • Date: Wed, 9 Feb 2005 09:27:24 -0500 (EST)
  • Organization: University of Tromsų
  • References: <cua579$hgs$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

I reproduced your first output

In[1]:=
{$System,$Version,$MachineType,$ProcessorType}

Out[1]=
{Microsoft Windows,5.1 for Microsoft Windows (October 25, 2004),PC,x86}

But the bug you report was not found. Mathematica reported correctly 
that the integral did not converge on the given range.

I have no explanation, only a response on your OS question. I can not 
find the bug, still I am running the same version on the same OS.

Arne Eide



Gennady Stupakov wrote:
> I tried to post this a few days ago, but it looks like it did not make it.
> 
> Here is a couple of bugs that I found recently in Mathematica 5.1.
> 
> In[13]:={$System, $Version, $MachineType, $ProcessorType}
> Out[13]={"Microsoft Windows","5.1 for Microsoft Windows (October 25, 2004)",
> "PC", "x86"}
> 
> First, I integrate E^(I*x^2),  from 0 to Infinity and get zero, which, of
> course, is wrong.
> 
> In[1]:={Integrate[E^(I*x^2), {x, 0, Infinity}], Integrate[Cos[x^2] +
> I*Sin[x^2], {x, 0,
> Infinity}]}
> Out[1]={0, (1/2 + I/2)*Sqrt[Pi/2]}
> 
> Second is a more complicated integral that I recently encounted in my
> research.
> 
> In[2]:=Integrate[E^(a*Cos[x] - b*Cos[2*x]), {x, 0, 2*Pi},
> GenerateConditions -> True]
> Out[2]=If[Re[a] < Re[b], 2*Pi*BesselI[0, -a + b], Integrate[E^(a*Cos[x] -
> b*Cos[2*x]), {x, 0,
> 2*Pi},Assumptions -> Re[a] >= Re[b]]]
> 
> Let us check this result comparing it with numerical integration for, say,
> b=2 and a=1:
> 
> In[3]:=
> b = 2.;
> a = 1.;
> {Integrate[E^(a*Cos[x] - b*Cos[2*x]), {x, 0, 2*Pi}], NIntegrate[E^(a*Cos[x]
> + b*Cos[2*x]),
> {x, 0, 2*Pi}]}
> Out[5]={7.95493, 20.8711}
> 
> Again, the analytical result is wrong.
> 
> It would be interesting if those bugs are reproduced on other OS and/or
> versions of Mathematica.
> 
> Gennady.
> 
> 


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