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MathGroup Archive 2003

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Re: Log[Exp[r]] <> r?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg39287] Re: Log[Exp[r]] <> r?
  • From: "Steve Luttrell" <luttrell at _removemefirst_westmal.demon.co.uk>
  • Date: Sun, 9 Feb 2003 04:50:49 -0500 (EST)
  • References: <b22jou$6bh$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Log[Exp[r]] doesn't simplify to r in general because Log has a branch point
at the origin. However if you specify that r is a Real then you get what you
want:

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

gives the output

r

--
Steve Luttrell
West Malvern, UK

"Jonathan Greenberg" <greenberg at ucdavis.edu> wrote in message
news:b22jou$6bh$1 at smc.vnet.net...
> Hi there, why is it when I enter Log[Exp[r]] (or use Simplify or
> FullSimplify) I don't get r?  If I do Log[Exp[2]] I get 2!
>
> --j
>
> --
> Jonathan Greenberg
> Graduate Group in Ecology, U.C. Davis
> http://www.cstars.ucdavis.edu/~jongreen
> http://www.cstars.ucdavis.edu
> AIM: jgrn307 or jgrn3007
> MSN: jgrn307 at msn.com or jgrn3007 at msn.com
>
>




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