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Re: Absolute Value of Complex Numbers

• To: mathgroup at smc.vnet.net
• Subject: [mg35206] Re: Absolute Value of Complex Numbers
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Tue, 2 Jul 2002 02:12:04 -0400 (EDT)
• Organization: Universitaet Leipzig
• References: <afp0oh$h08$1@smc.vnet.net>
• Reply-to: kuska at informatik.uni-leipzig.de
• Sender: owner-wri-mathgroup at wolfram.com

Hi,

> 
> Abs[2 Exp[3 * i]]
> answer = 2
> 
> Abs[2 Exp[k * i]]
> answer = 2 Exp[-Im[k]]
> 
> Isn't the second answer supposed to be the same with the first one,

No, because k can be complex as well and Exp[I*(Re[k]+I*Im[k]) will give
you
Exp[-Im[k]]

> regardless with the value of k? How do I make the second calculation give me
> the right answer?

Abs[2 Exp[k*I]] // FullSimplify[#, Element[k, Reals]] &


Regards
  Jens