Re: Why all the if's the answer

*To*: mathgroup at smc.vnet.net*Subject*: [mg70823] Re: Why all the if's the answer*From*: "dimitris" <dimmechan at yahoo.com>*Date*: Sat, 28 Oct 2006 23:37:55 -0400 (EDT)*References*: <ehs31u$oe4$1@smc.vnet.net>

Dear Aaron, With all these Log and Sqrt and so many parameters around, I think it is not very reliable to use GenerateConditions->False (except you want the finite part of the integral that many times the setting GenerateConditions->False gives or you are sure that your integral converge in the Riemann sense and you don't want Mathematica to search for it) BTW, Timing[Integrate[(Sin[x]/(1 + x^2)^m)*BesselJ[n, x], {x, 0, Infinity}]][[1]] 60.266 Second Timing[Integrate[(Sin[x]/(1 + x^2)^m)*BesselJ[n, x], {x, 0, Infinity}, GenerateConditions -> False]][[1]] 6.281 Second So, you see the advantage of GenerateConditions->False setting; the time. But, see now the drawback; Integrate[(Cos[x]/x)*Exp[(-s)*x], {x, 0, Infinity}, GenerateConditions -> False] (1/2)*(-EulerGamma - Log[1 + 1/s^2] + Log[1/s^2]) Integrate[(Cos[x]/x)*Exp[(-s)*x], {x, 0, Infinity}] Integrate::idiv: Integral of Cos[x]/x)*Exp[(-s)*x] does not converge on {0,8} Cos[x]/x)*Exp[(-s)*x] Regards Dimitris