Principal Value integral

*To*: mathgroup at smc.vnet.net*Subject*: [mg52361] Principal Value integral*From*: Carlo Teubner <AskMeAndIllTellYou. at example.com>*Date*: Wed, 24 Nov 2004 02:32:35 -0500 (EST)*Organization*: Oxford University, England*Sender*: owner-wri-mathgroup at wolfram.com

The following Principal Value integral does not appear to give the correct result. Integrate[1/(x^3-1), {x, -Infinity, Infinity}, PrincipalValue->True] This gives I Pi / 3, which surely can't be right since the answer should be real. When doing it numerically, it gives the right answer: <<NumericalMath`CauchyPrincipalValue` CauchyPrincipalValue[1/(x^3-1), {z, -Infinity, {1}, Infinity}] This gives -1.8138 which is the correct answer (it's -Pi/Sqrt[3]). Any explanations? Is this a bug or am I missing something? Carlo

**Follow-Ups**:**Re: Principal Value integral***From:*DrBob <drbob@bigfoot.com>