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Re: Using Coefficient on an equation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg95475] Re: [mg95433] Using Coefficient on an equation
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Mon, 19 Jan 2009 03:00:41 -0500 (EST)
  • Reply-to: hanlonr at cox.net

f = a*x^2 + b*x + c == 0;

Coefficient[f[[1]], x^2]

a


Bob Hanlon

---- carlos at colorado.edu wrote: 

=============
If f=a*x^2+b*x+c, Coefficient[f,x^2] obviously returns a.
But if f=a*x^2+b*x+c==0, it returns 0.

The problem arose using the Calculus`VariationalMethods` package.
It (unfortunately) returns the Euler-Lagrange equations as
such, so I have to remove the useless ==0 appendage for
Coefficient to work properly. Is there a simple direct way out?


--

Bob Hanlon



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