
Wrong result of Integrate with assumptions  my fault?
Posted:
Jul 18, 2013 2:44 AM


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[res1res2/.{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 (Ãcole et Observatoire des Sciences de la Terre) IPG (Institut de Physique du Globe)  alain.cochard@unistra.fr 5 rue RenÃ© Descartes [bureau 106]  Phone: +33 (0)3 68 85 50 44 F67084 Strasbourg Cedex, France  Fax: +33 (0)3 68 85 01 25

