Re: Integrate gives wrong results for a simple polynomial
- To: mathgroup at smc.vnet.net
- Subject: [mg117952] Re: Integrate gives wrong results for a simple polynomial
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Tue, 5 Apr 2011 06:45:02 -0400 (EDT)
Appears to work fine here. What result did you get and with which system and version. {$Version, $ReleaseNumber} {"8.0 for Mac OS X x86 (64-bit) (February 23, 2011)", 1} $Assumptions = p > 0; Integrate[Subscript[x, 1]*(1 + y)^2, {y, -1, 1}] (8*Subscript[x, 1])/3 $Assumptions = p > 0; Integrate[x*(1 + y)^2, {y, -1, 1}] (8*x)/3 $Assumptions = True; Integrate[Subscript[x, 1]*(1 + y)^2, {y, -1, 1}] (8*Subscript[x, 1])/3 Integrate[(1 + y)^2, {y, -1, 1}] 8/3 Bob Hanlon ---- Micket <micketeer at gmail.com> 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?