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MathGroup Archive 2005

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Re: Simplify problems for checking easy equalities...

  • To: mathgroup at smc.vnet.net
  • Subject: [mg53886] Re: Simplify problems for checking easy equalities...
  • From: "Kevin J. McCann" <kjm at KevinMcCann.com>
  • Date: Wed, 2 Feb 2005 06:25:50 -0500 (EST)
  • References: <ctnhah$erh$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

David,

While your approach works, the identity is true regardless of the values 
of x and n; so, it is curious that Simplify does not get it for the more 
general case.

Kevin

David Park wrote:
> Cyrus,
> 
> Include the proper assumptions in the Simplify statement.
> 
> Simplify[Log[x^n] - n*Log[x], n \[Element] Integers && x > 0]
> 0
> 
> David Park
> djmp at earthlink.net
> http://home.earthlink.net/~djmp/ 
> 
> From: Cyrus Erik Eierud [mailto:cyruserik at tele2.se]
To: mathgroup at smc.vnet.net
> 
> Please Help!
> 
> Thanks for all great answers I've already found here!
> My problem is that I can not simplify what to me seems as a very
> simple equality task. This is what I want Mathematica to return zero
> for:
> 
> in[1]:= FullSimplify[Log[x^n] - n*Log[x]]
> 
> out[1]= -n Log[x] + Log[x^n])
> 
> I have used Simplify to check equalities, but the one above (and many
> other equations similar to the one above) just don't simplify. Am I
> doing anything wrong or does anyone know of a better way to check
> equalities?
> 
> Appreciate any help,
> Cyrus Eierud, Student
> cyruserik at tele2.se
> 
> 
> 


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