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Re: How do I force Log[Exp[x]]=x

• To: mathgroup at smc.vnet.net
• Subject: [mg22033] Re: How do I force Log[Exp[x]]=x
• From: Harald Giese <giese at ifm.uni-hamburg.de>
• Date: Fri, 11 Feb 2000 02:38:15 -0500 (EST)
• Organization: Institut fuer Meereskunde, Universitaet Hamburg
• References: <87tp95$5ia@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Bart Killam wrote:
> 
>   For real x, Log[Exp[x]]=x. For general complex x
> Mathematical leaves this expression unevaluated. I
> have tried Log[Exp[x/;Im[x]=0]], but this give a result
> of 0.
> 
>   How do I tell Mathematica that I want the expression
> simplied for real x ? Thanks for any help.


Hi,

This does the job:

Simplify[Log[Exp[x]], x \[Element] Reals]


/Harald
-- 

Harald Giese
Email: giese at dkrz.de
Phone: +49 (0)40 42838 5796; Fax: +49 (0)40 5605724
Institut fuer Meereskunde der Universitaet Hamburg
(Institute of Oceanography of the University of Hamburg)
Troplowitzstrasse 7, D-22529 Hamburg