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Re: How to make Mathematica to return "Log[Exp[x]]" as x?

• To: mathgroup at smc.vnet.net
• Subject: [mg5710] Re: [mg5669] How to make Mathematica to return "Log[Exp[x]]" as x?
• From: Peder Thusgaard Ruhoff <ptk at dit.ou.dk>
• Date: Sat, 11 Jan 1997 14:29:07 -0500
• Sender: owner-wri-mathgroup at wolfram.com

On Tue, 7 Jan 1997, Cheng Li wrote:

> Date: Tue, 7 Jan 1997 11:22:46 -0500
> From: Cheng Li <chengli at uab.edu>
To: mathgroup at smc.vnet.net
> To: mathgroup at smc.vnet.net
> Subject: [mg5710] [mg5669] How to make Mathematica to return "Log[Exp[x]]" as x?
> 
> Dear friends, suppose x is a variable and when I type "Log[Exp[x]]" and then 
> enter, Mathematica gives me "Log[Exp[x]]" back. Could you please tell me how 
> to let Mathematica to return "Log[Exp[x]]" as x?
> Thank you very much.
> Cheng Li
> chengli at uab.edu
> 
> 

Dear Cheng Li,

Use PowerExpand.

In[1]:= Log[Exp[x]] // PowerExpand

Out[1]= x

Note that PowerExpand does not pay attention to branch cuts.

Peder

-------------------------------------+--------------------------------------
Peder Thusgaard Ruhoff, Ph.D.        | Phone:  (+45) 65 57 35 43
Department of Information Technology | Fax:    (+45) 66 15 76 97 
Odense University                    | 
Campusvej 55                         | E-mail: ptk at dit.ou.dk
DK-5230 Odense M, DENMARK            | URL:    http://www.dit.ou.dk/~ptk/
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