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Re: Approximation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg116479] Re: Approximation
  • From: Alexei Boulbitch <alexei.boulbitch at iee.lu>
  • Date: Wed, 16 Feb 2011 06:44:41 -0500 (EST)

The operators Series[]//Normal will do the job for you. For example:

expr = 1/Sqrt[R^2 + G^2];
Simplify[Series[expr, {R, 0, 2}], Assumptions ->  G>  0]
Simplify[Series[expr, {R, 0, 2}] // Normal, Assumptions ->  G>  0]

SeriesData[R, 0, {G^(-1), 0, Rational[-1, 2] G^(-3)}, 0, 3, 1]

1/G - R^2/(2 G^3)

Have fun. Alexei


Is there a way to tell Mathematica to simplify and approximate an
expression assuming things such as "R is a lot smaller than G"/ R<<G ?
If not so, how would you approach the problem?

Thanks

-- 
Alexei Boulbitch, Dr. habil.
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