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

• To: mathgroup at smc.vnet.net
• Subject: [mg5785] Re: How to make Mathematica to return "Log[Exp[x]]" as x?
• From: David Pearson <sgspedav at reading.ac.uk>
• Date: Sat, 18 Jan 1997 14:58:37 -0500
• Organization: University of Reading, U.K.
• Sender: owner-wri-mathgroup at wolfram.com

On 7 Jan 1997, Cheng Li wrote:

> 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?

Hi,

Try ComplexExpand[ Log[Exp[x]] ].

The reason it doesn't default to x is that Log is a
many-valued function in complex analysis.

Regards,
David.

 David Pearson,            Phone: (0)1743 318741    
 ESSC, PO Box 227,         Fax:   (0)1734 755865
 University of Reading,    email: sgspedav at rdg.ac.uk           
 Reading, RG6 6AB, UK.     internet: http://www.nerc-essc.ac.uk/~dwcp/