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Re: Bug of Integrate

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82752] Re: Bug of Integrate
  • From: roland franzius <roland.franzius at uos.de>
  • Date: Tue, 30 Oct 2007 03:34:56 -0500 (EST)
  • Organization: Universitaet Hannover
  • References: <fg4dfv$6c3$1@smc.vnet.net>

Miguel wrote:
> 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?

No, my Windo*s version 6.01 yields the correct integral value 0

Integrate[3*Sign[Cos[t]],{t,0,2Pi}]

= 6 * (pi/2- pi + pi/2)

since x/sqrt(x^2) = sign(x)

-- 

Roland Franzius


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