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MathGroup Archive 1996

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Re: ComplexExpand

  • To: mathgroup at smc.vnet.net
  • Subject: [mg5338] Re: [mg5302] ComplexExpand
  • From: Daniel Lichtblau <danl>
  • Date: Wed, 27 Nov 1996 01:47:52 -0500
  • Organization: wolfram.com
  • Sender: owner-wri-mathgroup at wolfram.com

E. Neely Atkinson wrote:
> 
> Can anyone explain to me why the following two
> examples behave differently? Thanks.
> 
> Mathematica 2.2 for IBM RISC System/6000
> Copyright 1988-93 Wolfram Research, Inc.
>  -- Terminal graphics initialized --
> 
> In[1]:= ComplexExpand[Log[1 / E^x]]
> 
> Out[1]= -x
> 
> In[2]:= ComplexExpand[Log[1 / (2 E^x)]]
> 
>              1
> Out[2]= Log[----]
>                x
>             2 E
> 
> 
> 
>          E. Neely Atkinson
>          neely at biomath.mdacc.tmc.edu

Looks like a minor bug. The result is tolerable because it is separated
into explicitly real and imaginary parts. The latter just happens to be
zero, because x is assumed real.

Works better in version 3.0.

In[2]:=  ComplexExpand[Log[1 / (2 E^x)]]
Out[2]= -x - Log[2]

In[3]:= $Version
Out[3]= Linux 3.0 (October 4, 1996)

Daniel Lichtblau
Wolfram Research
danl at wolfram.com


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