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MathGroup Archive 2002

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Re: Absolute Value of Complex Numbers

  • To: mathgroup at smc.vnet.net
  • Subject: [mg35217] Re: Absolute Value of Complex Numbers
  • From: "John Doty" <jpd at w-d.org>
  • Date: Tue, 2 Jul 2002 02:13:18 -0400 (EDT)
  • References: <afp0oh$h08$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

In article <afp0oh$h08$1 at smc.vnet.net>, "Kyle Davis"
<kyledavis at nowhere.com> wrote:

> 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,
> regardless with the value of k?

Only if k is real.

> How do I make the second calculation give me the right answer?

In[1]:= ComplexExpand[Abs[2 Exp[k * I]]]

Out[1]= 2

ComplexExpand[] performs the expansion assuming all variables represent
real numbers.

-- 
| John Doty		"You can't confuse me, that's my job."
| Home: jpd at w-d.org
| Work: jpd at space.mit.edu


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