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NInegrate Bug

• To: mathgroup at smc.vnet.net
• Subject: [mg116439] NInegrate Bug
• From: "Kurt TeKolste" <tekolste at fastmail.net>
• Date: Tue, 15 Feb 2011 06:34:50 -0500 (EST)
• References: <201102121019.FAA20109@smc.vnet.net> <ij83f7$o6$1@smc.vnet.net>

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

• References:
  • Nonorthogonal Eigenvectors
    • From: "Kevin J. McCann" <kjm@KevinMcCann.com>