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MathGroup Archive 2005

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Re: symbolic approximation (formular manipulation)

  • To: mathgroup at smc.vnet.net
  • Subject: [mg55051] Re: symbolic approximation (formular manipulation)
  • From: Paul Abbott <paul at physics.uwa.edu.au>
  • Date: Thu, 10 Mar 2005 05:25:18 -0500 (EST)
  • Organization: The University of Western Australia
  • References: <d0mnef$71b$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

In article <d0mnef$71b$1 at smc.vnet.net>, Zhe Hu <iamhuzhe at gmail.com> 
wrote:

> A formula in electrical engineering can be simplified after assuming,
> e.g. R1<<R2, within 10% error tolerance.
> 
> How this kind of "simplify" or approximation can be performed by Mathematica?
> 
> For example, R1<<R2, R2<<R3
> 
> R1+R2                      R2                                      R2
> ---------------  --->  ------------------  ---------> ------------------
> R1(R2+R3)               R1(R2+R3)                       R1 R3

Use Series.

  Normal[Series[(R1 + R2)/(R1 (R2 + R3)), {R1, 0, -1}, {R2, 0, 1}]]

Cheers,
Paul

-- 
Paul Abbott                                   Phone: +61 8 6488 2734
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