
From:  Carlo de Falco 
Subject:  Re: phase space 
Date:  Fri, 3 Apr 2009 15:26:39 +0200 
On 3 Apr 2009, at 14:55, Johannes Wolfgang Woger wrote:
Hi, I am an newby. How can I obtain a plot of the phase portrait of LotkaVolterra: octave:92> function xdot = f(x,t)a = 4; b = 4; c = 4; d = 8; E = 1; K = 1; xdot = zeros(2,1); xdot(1) = x(1)*(ab*x(2)E*x(1)); xdot(2) = x(2)*(d*x(1)cK*x(2)); endfunctionoctave:93> octave:93> t = linspace(0,50,100); octave:94> x = lsode("f", [2,1],t); octave:95> plot(t,x);
plot(x(:,1), x(:,2)); xlabel("x_1"); ylabel("x_2");but I would suggest using a few more time steps if you want a nice looking spiral...
Thanks
HTH, c.
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