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

• To: mathgroup at smc.vnet.net
• Subject: [mg22026] Re: [mg21988] How do I force Log[Exp[x]]=x
• From: Laurence Lours <lours at bruyeres.cea.fr>
• Date: Fri, 11 Feb 2000 02:38:09 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

With Mathematica 4, you have just to do 
Simplify[Log[Exp[x]],x\[Element]Reals]
and it returs x.

Laurence Lours


> From mathgroup-adm at smc.vnet.net Thu Feb 10 08:55 MET 2000
> Date: Thu, 10 Feb 2000 02:25:32 -0500 (EST)
> From: sasrbk at unx.sas.com (Bart Killam)
To: mathgroup at smc.vnet.net
> To: mathgroup at smc.vnet.net
> Subject: [mg22026] [mg21988] How do I force Log[Exp[x]]=x
> 
> 
>   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.
> -- 
> Bart Killam                            Work:  919-677-8000 x7538
> SAS Institute Inc.                     Fax:   919-677-8123
> SAS Campus Dr., R5115                  Email: sasrbk at unx.sas.com
> Cary NC 27513-8000   
> 
>