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Re: Coefficient...

• To: mathgroup at smc.vnet.net
• Subject: [mg79686] Re: Coefficient...
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Thu, 2 Aug 2007 03:41:28 -0400 (EDT)
• Organization: The Open University, Milton Keynes, UK
• References: <f8n1i0$j87$1@smc.vnet.net>

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
> 

The following might help:

In[1]:= fx = a*x^2 + d*x*y + 2*c*x + b*c*x*z;
Coefficient[fx, x]
Coefficient[Plus @@ Cases[fx, p_ /; FreeQ[p, y] && FreeQ[p, z]], x]

Out[2]= 2 c + d y + b c z

Out[3]= 2 c

Regards,
Jean-Marc