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Re: log expression not simplified

  • To: mathgroup at smc.vnet.net
  • Subject: [mg115688] Re: log expression not simplified
  • From: Michael Weyrauch <michael.weyrauch at gmx.de>
  • Date: Tue, 18 Jan 2011 05:51:27 -0500 (EST)
  • References: <ih16cv$jke$1@smc.vnet.net>

The following works and produces -1 as a result

Simplify[FullSimplify[ComplexExpand[Log[a/b]/Log[b/a]]],
  Assumptions -> {a > 0, b > 0}]

Its probably so complicated because of the cut of Log[] on the real axis 
(in the complex plane).

Michael

Am 17.1.2011 11:41, schrieb Praeceptor:
> Sorry, can anybody help me understand why
>
> Simplify[Log[a/b]/Log[b/a], Assumptions ->  {a>  0, b>  a}]
>
> doesn't reduce to -1 ??
> Thanks (it's for a simple Carnot cycle calculation...)!
>



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