RE: How to get the real part of an integral?

*To*: mathgroup at smc.vnet.net*Subject*: [mg48474] RE: [mg48453] How to get the real part of an integral?*From*: "David Park" <djmp at earthlink.net>*Date*: Tue, 1 Jun 2004 03:02:50 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Andy, How about... step1 = Integrate[1/(1 + x^2 + x^4), x]; ComplexExpand[Re[step1], TargetFunctions -> {Re, Im}]; f[x_] = Simplify[%] (1/12)*((-Sqrt[3])*ArcTan[2 - x, (-Sqrt[3])*x] + Sqrt[3]*ArcTan[2 - x, Sqrt[3]*x] - Sqrt[3]*ArcTan[2 + x, (-Sqrt[3])*x] + Sqrt[3]*ArcTan[2 + x, Sqrt[3]*x] - 3*Log[1 - x + x^2] + 3*Log[1 + x + x^2]) Plot[f[x], {x, -10, 10}]; You don't need Algebra`ReIm` and you will often have to use ComplexExpand on complex analysis problems. Think of ComplexExpand as being more a ComplexSimplify command. Notice that Mathematica used the two argument ArcTan, which is a pretty neat function! David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: Andy Kowar [mailto:ankowar at yahoo.com] To: mathgroup at smc.vnet.net I am trying to get the real part of an integral (see below). << Algebra`ReIm` Integrate[1/(1 + x^2 + x^4), x] Re[%] I am getting the error: "$IterationLimit::itlim: Iteration limit of 4096 exceeded." Any advice? AK