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Re: complex analysis problem in mathematica 3.0

  • To: mathgroup at smc.vnet.net
  • Subject: [mg48502] Re: complex analysis problem in mathematica 3.0
  • From: BranasMan <branasREmoVe at mail.inet.hr>
  • Date: Wed, 2 Jun 2004 04:22:21 -0400 (EDT)
  • References: <c9ec75$g9q$1@smc.vnet.net> <c9haqn$1b8$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

On Tue, 1 Jun 2004 07:21:59 +0000 (UTC) 
klishko at mail.ru (Alex Klishko)
wrote:

>I think, it confuses because of a variable w may also be a comlex number.
>If w is a real try ComplexExpand -fuction.
>For example:
>
>H = 1 / (s^3 + 2s^2 + 2s + 1) /. s -> \jw 
>ComplexExpand[%]

w IS real,but i can't get mathematica to see that, and when i do
ComplexExpand[%] i get the following:

(1/Abs[1 + 2Iw - 2w^2 - Iw^3]^2 - 
    (2Iw)/Abs[1 + 2Iw - 2w^2 - Iw^3]^2 - 
    (2w^2)/Abs[1 + 2Iw - 2w^2 - Iw^3]^2 + 
    (Iw^3\)/Abs[1 + 2Iw - 2w^2 - Iw^3]^2)

does anybody manage to get this thing right?
i'm a little lost...


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