Re: complex analysis problem in mathematica 3.0
- To: mathgroup at smc.vnet.net
- Subject: [mg48470] Re: complex analysis problem in mathematica 3.0
- From: Paul Abbott <paul at physics.uwa.edu.au>
- Date: Tue, 1 Jun 2004 03:02:46 -0400 (EDT)
- Organization: The University of Western Australia
- References: <c9ec75$g9q$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
In article <c9ec75$g9q$1 at smc.vnet.net>,
BranasMan <branasREmoVe at mail.inet.hr> wrote:
> i have a complex function:
>
> H(s)=1 / (s^3 + 2s^2 + 2s + 1)
>
> whan i replace "s" with j*w (j=sqrt(-1)) i get:
>
> H=1 / (1 + j2w -2w^2 - jw^3)
>
> i would like to get that function in shape of :
> H=something + j*something_else i.e. the complex
> and real part apart.
>
> i played with Re and Im,but it seems that the fact that
> "w" is a variable confuses mathematica?!
For your function,
h[s_] = 1/(s^3 + 2s^2 + 2s + 1);
You can obtain the real and imaginary parts as follows:
Simplify @ ComplexExpand @ Through @ {Re, Im} @ h[I w]
Cheers,
Paul
--
Paul Abbott Phone: +61 8 9380 2734
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