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## An other problem

 From: John W. Eaton Subject: An other problem Date: Thu, 19 Jun 2003 23:17:34 -0500

```On 20-Jun-2003, Yann Lamontagne a.k.a. daume <address@hidden> wrote:

| I am trying to plot
| function xdot = lorenz(x)
| xdot(1) = 10*x(2) - 10*x(1)
| xdot(2) = x(1)*2.666 - x(3)*x(1) - x(2)
| xdot(3) = x(1)*x(2) - 28*x(3)
| end
| solution=lsode( "lorenz",[1, 1, 1], t = linspace(0.0,100, 5000))
| gset parametric
| gsplot(solution)
|
| the solution seems to have two sets of data and I believe it is plotting
| the wrong set, do anyone know how to fix that?

I think you are doing the right thing, but the set of equations that
you are using don't look like the same ones I have seen before.  Also,
starting point is critical to getting a interesting behavior and a
pretty plot.  If I use

function y = lorenz (x, t)
y = [10 * (x(2) - x(1));
x(1) * (28 - x(3));
x(1) * x(2) - 8/3 * x(3)];
endfunction
x = lsode ("lorenz", [3; 15; 1], (0:0.01:25)');
gset parametric
gsplot x

I get a plot that looks a lot like the one on the Octave home page
(but with 3d axes).

jwe

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