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MathGroup Archive 2007

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Re: Coefficient...

  • To: mathgroup at smc.vnet.net
  • Subject: [mg79635] Re: [mg79601] Coefficient...
  • From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
  • Date: Wed, 1 Aug 2007 04:51:17 -0400 (EDT)
  • References: <200707311002.GAA19571@smc.vnet.net>

On 31 Jul 2007, at 12:02, Bruno Campanini wrote:

> Given fx:=ax^2 + dxy + 2cx + bcxz
> Coefficient[fx,x] gives   dy + 2c + bcz   but I only need 2c.
>
> Without any If clause, is it possible to get Coefficient not
> to look on terms containing y or z?
>
> Bruno
>

Coefficient itself is not really well suited for this,  but you can  
use either CoefficientList or CoefficientArrays:

f = a x^2 + d x y + 2 c x + b c x z

CoefficientArrays[f, {x, y, z}][[2, 1]]

2 c

CoefficientList[f, {x, y}][[2, 1, 1]]
2 c

Andrzej Kozlowski


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