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MathGroup Archive 2002

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Solve (on Mathematica 4.1 Windows XP)?

  • To: mathgroup at
  • Subject: [mg33047] Solve (on Mathematica 4.1 Windows XP)?
  • From: michael_chang86 at (Michael Chang)
  • Date: Wed, 27 Feb 2002 00:48:05 -0500 (EST)
  • Sender: owner-wri-mathgroup at

Hi everyone,

I've noticed a problem that I've been having when trying to use
Solve[] on Mathematica 4.1 for Windows XP.  :(

Suppose I have

In[1]:= Zf=(s(C1+C2)R2+1)/(s(s C1 C2 R2+C2));zf=(s c1 r2+1)/(s(s c1 c2
r2+c1+c2)); diff=Zf-zf;

(Sorry for the 'improper' (Capital) naming convention used above!)

Basically, I would like to find out under what conditions Zf will
(can?) be equal to zf.  So I pick three points for 's', say {1,2,3},
and do the following:

In[2]:= Solve[Thread[{diff/.{s->1},diff/.{s->2},diff/.{s->3}}=={0,0,0}],{c1,c2,r2}]

Here, I get a solution (which is omitted for brevity) which works upon
back substitution.  But if I pick some other points for 's', say
{Sqrt[2],Pi,3}, and try to solve for the same variables (c1,c2,r2)
Solve seems to hang ... and I can't seem to obtain more encouraging
results using GroebnerBasis either ...

Am I doing something wrong here?  If so, <blush> what?

Of course, any and all help would be greatly appreciated!



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