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Re: extracting fractional powers of series expansion?

• To: mathgroup at smc.vnet.net
• Subject: [mg78292] Re: [mg78225] extracting fractional powers of series expansion?
• From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
• Date: Wed, 27 Jun 2007 05:40:29 -0400 (EDT)
• References: <200706260832.EAA05639@smc.vnet.net>

On 26 Jun 2007, at 17:32, Tanim Islam wrote:

> Hi:
>
> How do I extract a given fractional power term in a series  
> expansion? For
> instance, I do a series expansion of a function about infinity. How  
> do I
> extract the -1/2 power term with, say, SeriesCoefficient. I am using
> Mathematica 6.
>
> Tanim Islam
>


For example:

f[x_] := ArcTanh[Sqrt[x]]

  s = SeriesCoefficient[Series[f[x], {x, Infinity, 3}], 5/2]

  1/5

Note that this is the coefficient of (1/x)^(5/2)

Andrzej Kozlowski

• References:
  • extracting fractional powers of series expansion?
    • From: Tanim Islam <tanim.islam@gmail.com>