Re: Bug of Integrate

*To*: mathgroup at smc.vnet.net*Subject*: [mg82742] Re: Bug of Integrate*From*: Peter Pein <petsie at dordos.net>*Date*: Tue, 30 Oct 2007 03:29:48 -0500 (EST)*References*: <fg4dfv$6c3$1@smc.vnet.net>

Miguel schrieb: > When I try to calculate the integral > > Integrate[Sqrt[1/Cos[t]^2]*3*Cos[t],{t,0,2Pi}] Mathematica 6.0.1 > yields -6*Pi. > > Simplifying the expresion resultrs Integrate[3,{t,0,2*Pi}] and It is > clear that the correct solution is 6*Pi. > > Is a bug of Version 6.0.1? > > Hi Miguel, I do not know, how you simplified the expression, but i get (with Sqrt[z^2]==Abs[z]): Sqrt[1/Cos[t]^2]*3*Cos[t] = 3*Sign[Cos[t]] and the Integral is 0 (which Version 5.2 calculates correctly). Peter