c6_nltvde.m

该程序是二阶琐相环的防震实例 仿真结果给出了二阶琐相环的相平面

w2b=0;w2c=0;
yd=0;y=0;
tfinal=50;
fs=100;
delt=1/fs;
npts=1+fs*tfinal;
ydv=zeros(1,npts);
yv=zeros(1,npts);
for i=1:npts
    t=(i-1)*delt;
    if t< 20
        ydd=4*exp(-t/2)-3*yd*abs(y)-9*y;
    else 
        ydd=4*exp(-t/2)-3*yd-9*y;
    end
    w1b=ydd+w2b;
    w2b=ydd+w1b;
    yd=w1b/(2*fs);
    w1c=yd+w2c;
    w2c=yd+w1c;
    y=w1c/(2*fs);
    ydv(1,i)=yd;
    yv(1,i)=y;
end
plot(yv,ydv)
xlabel('y(t)')
ylabel('dy/dt')