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

• To: mathgroup at smc.vnet.net
• Subject: [mg24458] Re: Why doesn't Log[ E^x ] = x ?
• From: Paul Abbott <paul at physics.uwa.edu.au>
• Date: Tue, 18 Jul 2000 00:59:02 -0400 (EDT)
• Organization: University of Western Australia
• References: <8jrdc2$e2t@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

In article <8jrdc2$e2t at smc.vnet.net>, "Christopher R. Carlen" 
<crcarle at sandia.gov> wrote:

> Hi:
> 
> E^Log[x] evaluates to x 
> 
> but
> 
> Log[ E^x ] evaluates to Log[ E^x ]
> 
> Why?

For a full answer, you might want to have a look at the paper by Helmer 
Aslaksen called "Can your computer do complex analysis?" at

   http://www.math.nus.edu.sg/aslaksen/helmerpub.shtml

I have a Notebook which implements all the tests in Aslaksen's paper, if 
you are interested.

Cheers,
   Paul

-- 
Paul Abbott                                   Phone: +61-8-9380-2734
Department of Physics                           Fax: +61-8-9380-1014
The University of Western Australia                
Nedlands WA  6907                      
AUSTRALIA                             http://physics.uwa.edu.au/~paul