duffing1.m

非线性动力学中lyapunov、duffing等方程的求解

clear all
pack 

global m c k w f a

m=1;
c=0.3;
a=1;
k=1;
w=1.2;
%f=0.32;


step=2*pi/w/20;

t=0:step:1000;

x01=1;x02=1;
x0=[x01;x02];

k0=0;

for f=0.2:0.0002:0.32


k0=k0+1
ff(k0)=f;

[T,X]=ode45('duffing01',t,x0);

xx=X(:,1);

N=length(t);

x01=X(N,1);
x02=X(N,2);
x0=[x01;x02];

xx1=xx((N-400):N);

nn=length(xx1);
nnnnn=fix(nn/20);

n=0;
for nnn=1:nnnnn
    nnnn=n+20;
    xxx1(k0,nnn)=xx1(nnnn);
end

end

figure
hold on
for k4=1:k0
    plot(ff,xxx1(:,k4),'b.')
end