Re: False result with Integrate ?

*To*: mathgroup at smc.vnet.net*Subject*: [mg8729] Re: False result with Integrate ?*From*: "Stephen P Luttrell" <luttrell at signal.dra.hmg.gb>*Date*: Sat, 20 Sep 1997 22:27:58 -0400*Organization*: Defence Evaluation and Research Agency*Sender*: owner-wri-mathgroup at wolfram.com

Gilles BARBIER <Gilles.Barbier at der.edfgdf.fr> wrote in article <5vt8tj$gjg at smc.vnet.net>... > Why : Integrate[Integrate[ Sqrt[(x-y)^2],{x,0,1}],{y,0,1}] > gives 0 with math2.2 or math3.0. > > The exact result is 1/3 !! It seems that Mathematica is simplifying Sqrt[(x-y)^2] to x-y. Try the following way of doing your integral: 2 Integrate[Integrate[ x-y,{x,y,1}],{y,0,1}] -- Stephen P Luttrell luttrell at signal.dra.hmg.gb Adaptive Systems Theory 01684-894046 (phone) Room EX21, DERA 01684-894384 (fax) Malvern, Worcs, WR14 3PS, U.K. http://www.dra.hmg.gb/cis5pip/Welcome.html