programs_14d.m

《Dynamical Systems with Applications using MATLAB》源代码

% Chapter 14 - Poincare Maps and Nonautonomous Systems in the Plane.
% Programs_14d - Poincare section for the Duffing system.
% Copyright Birkhauser 2004. Stephen Lynch.

% Poincare section for the Duffing system (Fig. 14.10).
clear
deq=inline('[x(2);x(1)-0.3*x(2)-(x(1))^3+0.5*cos(1.25*t)]','t','x');
options=odeset('RelTol',1e-4,'AbsTol',1e-4);
[t,xx]=ode45(deq,[0:(2/1.25)*pi:(4000/1.25)*pi],[1,0]);
plot(xx(:,1),xx(:,2),'.','MarkerSize',1)
fsize=15;
axis([-2 2 -2 2])
xlabel('x','FontSize',fsize)
ylabel('y','FontSize',fsize)
title('Poincare Section of the Duffing System')

% End of Programs_14d.