Wrong result of Integrate with assumptions -- my fault?
- To: mathgroup at smc.vnet.net
- Subject: [mg131395] Wrong result of Integrate with assumptions -- my fault?
- From: Alain Cochard <Alain.Cochard at unistra.fr>
- Date: Thu, 18 Jul 2013 03:01:07 -0400 (EDT)
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Dear group -- In the following, it seems adding the assumption that w is real spoils the result: res1=Integrate[t*Exp[I w t],{t,a,b}, Assumptions-> a<b] ; res2=Integrate[t*Exp[I w t],{t,a,b}, Assumptions-> a<b && Element[w,Reals]]; Chop[N[res1-res2/.{a->-1, b->2, w->3}]] gives 0. + 0.691355 I (I tried Mathematica 7, 8, 9 installed on 3 different GNU/Linux machines). >From the various tests I did, it seems that the real parts are always identical while the imaginary parts differ in the case a < 0. Was this to be expected? Am I not allowed to make this assumption? Thank you. -- EOST (�cole et Observatoire des Sciences de la Terre) IPG (Institut de Physique du Globe) | alain.cochard at unistra.fr 5 rue René Descartes [bureau 106] | Phone: +33 (0)3 68 85 50 44 F-67084 Strasbourg Cedex, France | Fax: +33 (0)3 68 85 01 25