Groups > comp.soft-sys.math.mathematica > #1475

Re: Integrate gives wrong results for a simple polynomial

From	Daniel Lichtblau <danl@wolfram.com>
Newsgroups	comp.soft-sys.math.mathematica
Subject	Re: Integrate gives wrong results for a simple polynomial
Date	2011-04-05 10:42 +0000
Organization	Steven M. Christensen and Associates, Inc and MathTensor, Inc.
Message-ID	<inerm4$j58$1@smc.vnet.net> (permalink)

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Micket wrote:
> I have had the bad luck to discover a strange bug (?) when computing
> some integrals with mathematica.
> I simplified it as far as i could;
> $Assumptions = p > 0; Integrate[Subscript[x, 1]*(1 + y)^2, {y, -1, 1}]
> 
> If i change anything else, be it the assumption (yes, it is a
> completely unrelated variable), the subscript, the integration limits,
> the exponent, the addition, it works out the correct answer.
> 
> It also takes a significant time (a few seconds) to compute this
> integral.
> 
> Does anyone have an explanation for this behavior?

What version? I cannot reproduce it in 8.0.1. I guess I don't even know 
what the "it" is, since you did not indicate what result you obtained. 
[Note to all readers: Don't do that. Nobody likes to guess.]

I also cannot reproduce any problem in previous versions, for the simple 
reason that at the moment I cannot run any such; our machine with those 
caught a cold last week and might be suffering lingering after effects.

So my best guess is this was a bug that, at some point, got fixed.

Daniel Lichtblau
Wolfram Research

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Re: Integrate gives wrong results for a simple polynomial Daniel Lichtblau <danl@wolfram.com> - 2011-04-05 10:42 +0000
  Re: Integrate gives wrong results for a simple polynomial Scott Hemphill <hemphill@hemphills.net> - 2011-04-06 09:13 +0000

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