Re: Why doesn't Log[ E^x ] = x ?

*To*: mathgroup at smc.vnet.net*Subject*: [mg24241] Re: Why doesn't Log[ E^x ] = x ?*From*: "Kevin J. McCann" <kevinmccann at home.com>*Date*: Tue, 4 Jul 2000 15:22:05 -0400 (EDT)*References*: <8jrdc2$e2t@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Because the Log, considered as a complex function, is multivalued. E.g. Log[E^2]=2 but Log[E^(2+2Pi I)]=2 that is Mathematica's answer, rather than (2+2Pi I) which is not on the principle branch. And Log[E^(I 2Pi)]=0 not I 2Pi When you try Log[E^x] Mathematica doesn't know enough about x to answer; so it doesn't. Kevin "Christopher R. Carlen" <crcarle at sandia.gov> wrote in message news:8jrdc2$e2t at smc.vnet.net... > Hi: > > E^Log[x] evaluates to x > > but > > Log[ E^x ] evaluates to Log[ E^x ] > > Why? > > Thanks. > > P.S. Mathematica 3.0 > > _______________________ > Christopher R. Carlen > Sr. Laser/Optical Tech. > Sandia National Labs >