Re: Integrate gives wrong results for a simple polynomial
- To: mathgroup at smc.vnet.net
- Subject: [mg117936] Re: Integrate gives wrong results for a simple polynomial
- From: Daniel Lichtblau <danl at wolfram.com>
- Date: Tue, 5 Apr 2011 06:42:08 -0400 (EDT)
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