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Re: Coefficients in expressions

  • To: mathgroup at smc.vnet.net
  • Subject: [mg16822] Re: [mg16742] Coefficients in expressions
  • From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
  • Date: Tue, 30 Mar 1999 02:35:21 -0500
  • Sender: owner-wri-mathgroup at wolfram.com

A slight correction to the message I sent earlier. The definition of
coeffs should be:



In[1]:=
coeffs[Equal[x_,y_],z_]:=Coefficient[x,z]-Coefficient[y,z];
SetAttributes[coeffs,HoldFirst];


(There is no need for z to be a list as was the case in my origial message!)




On Wed, Mar 24, 1999, Virgil Stokes <virgil.stokes at neuro.ki.se> wrote:

>I have generated several expressions (equations) in the form of:
>
>   c1*x1 + c2*x1' + c3*x2 + c4*y1+...+a1*x1'+ a2*y1 + a5*x1 +... ==
f1*z1 +...
>
>where, the equations can be over 50 lines in length.
>I would like to have a procedure (say Coeffs[.]) that would
>allow me to specify as input the "names" in the equations. The
>output would be all the coefficients for that list of names.
>For example, for the above,
>
>  Coeffs[%,x1,x1',y1]
>
>would output,
>
>    x1: (c1+a5)
> x1': (c2+a1)
>  y1: (c4+a2)
>
>-- V. Stokes
>
>


Andrzej Kozlowski
Toyama International University
JAPAN
http://sigma.tuins.ac.jp/
http://eri2.tuins.ac.jp/



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