Re: Eliminate Variable
- From: John D'Errico <woodchips@xxxxxxxxxxxxxxxx>
- Date: Mon, 02 Jan 2006 15:01:35 GMT
In article <dpauef$f4d$1@xxxxxxxxxxxx>, Markus <no@xxxxxxxxx> wrote:
> Deepak wrote:
> > oops i am sorry i forgot to add the cosine factor in
> > the equations
> >
> > square(X2) + square(X3) -2 x X2 x X3xcos(X2xX3) =0;
> > square(X2) + square(X1) -2 x X2 x X1 xcos(X1xX2)=0;
> > square(X1) + square(X3) -2 x X1 x X3xcos(X1xX3)=0;
> >
> > Now I want to get a single equetion with variable X1 only.I want to
> > elimnate the variables X2 and X3 from these equations.Can someone
> > point me out to a function which does this in Matlab?I would be
> > obliged.
With the cos term in there, its far simpler. There
is now only a single solution. The good news is it
is very easy to write.
x1 = x2 = x3 = 0
You should be able to prove that no other solution
exists. (Hint: Look at any one of these equations.
It involves only two variables. When will it have a
solution?)
> Perhaps fsolve? In Maple it gives (without an initial guess)
>
> > sols := {x1 = -.8597006067, x2 = -.8597006067, x3 = 0.8597006067}
Sorry. But its not a solution.
x1 = -.8597006067;
x2 = -.8597006067;
x3 = 0.8597006067;
x1^2 + x2^2 - 2*x1*x2*cos(x1*x2)
ans =
0.3857
John
--
The best material model of a cat is another, or preferably the same, cat.
A. Rosenblueth, Philosophy of Science, 1945
Those who can't laugh at themselves leave the job to others.
Anonymous
.
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