Re: Bug of Integrate
- To: mathgroup at smc.vnet.net
- Subject: [mg82739] Re: Bug of Integrate
- From: Peter Breitfeld <phbrf at t-online.de>
- Date: Tue, 30 Oct 2007 03:28:09 -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? > The Integral should never be 6Pi but 0. Because your Integrand ist -3 in the Interval (-Pi/2, 3Pi/2) and +3 outside. If you simplify your integrand you get the result correct result 0. Your integand is effectively 3 Cos[t]/Abs[Cos[t]]. But I can't imagine, where the result -6Pi comes from. Must have to do with the undefined values at t=Pi/2 and t=3Pi/2 Gruss Peter -- ==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-== Peter Breitfeld, Bad Saulgau, Germany -- http://www.pBreitfeld.de