Re: A problem with an integral

*To*: mathgroup at smc.vnet.net*Subject*: [mg32806] Re: A problem with an integral*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Thu, 14 Feb 2002 01:43:20 -0500 (EST)*Organization*: Universitaet Leipzig*References*: <a4aurc$buv$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de*Sender*: owner-wri-mathgroup at wolfram.com

Hi, no you code is right but Mathematica take a different path to compute Integrate[Sin[x y], {y, 0, x}] with it's singularity at x==0 Regards Jens WhoamI wrote: > > Hi everybody, I have a problem with the next integral > > Integrate[Sin[x y],{x,0,1},{y,0,x}] > > that after expanding and factoring yields: > > \!\(1\/4\ \((EulerGamma - 2\ CosIntegral[1])\)\) > > and evaluating this I have -0.024398 > > To be sure about the answer I taked it other way: > > Integrate[ > TrigFactor[Integrate[Sin[x y], {y, 0, x}]] > , {x, 0, 1}] > > which yields > > \!\(1\/2\ \((EulerGamma - CosIntegral[1])\)\) > > and evaluating this I have 0.119906 > > Since I evaluated this integrals not numerically I > don't understand why the answers are different. Is > there something wrong with my code?. I would thanks a > lot for your answers... > > Cesar Guerra > Secc. Fisica PUCP-Lima > > __________________________________________________ > Do You Yahoo!? > Send FREE Valentine eCards with Yahoo! Greetings! > http://greetings.yahoo.com