以达芬振子为例

dafen = @(t,x,flag,force)[x(2);force*cos(1.2*t)-x(1)^3+x(1)-0.3*x(2)];

ff=0.23:0.002:0.40;%参数

axis([0.22,0.4,0.2,0.6]);

options=odeset('RelTol',1e-7);tt=2*pi/1.2;hold on

for j=1:length(ff)

   [t,x]=ode45(dafen,[0:tt/100:80*tt],[0,0],options,[],ff(j));

   i=2000:100:3000;

   plot(ff(j),x(i,2),'.')

end