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Re: NInegrate Bug

  • To: mathgroup at smc.vnet.net
  • Subject: [mg116443] Re: NInegrate Bug
  • From: Andrew Moylan <amoylan at wolfram.com>
  • Date: Wed, 16 Feb 2011 04:31:53 -0500 (EST)

Hi Kurt,

You should not encounter any problem in Mathematica 8. E.g.

In[1]:= NIntegrate[Sin[x^2], {x, -5, -2}]

Out[1]= -0.276859

In[2]:= N[Integrate[Sin[x^2], {x, -5, -2}]]

Out[2]= -0.276859

Andrew Moylan
Wolfram Research



On Feb 15, 2011, at 10:34 PM, Kurt TeKolste wrote:

> Has there been a resolution of the NIntegrate bug?
> 
> Apparently NIntegrate produces the negative of the right answer for
> integrations that start and end to the left of zero -- some of the time.
> (Cos[x] and Sin[x^2] get the wrong result, Sin[x] is good).
> 
> Since it is not clear what criterion Mathematica uses in deciding to
> give the wrong answer it is not clear when to use NIntegrate[] and when
> to use NIntegrate[*Sign[independent variable]].
> 
> And this calls into question any results for analysis that uses
> NIntegrate -- not a happy situation.
> 
> Kurt TeKolste
> 



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