function f=liutrack1(t,X) %liu system's self-synchronization
global p;
f=zeros(6,1);
x1=X(1);x2=X(2);x3=X(3);y1=X(4);y2=X(5);y3=X(6);
f(1)=10*(x2-x1);
f(2)=40*x1-x1*x3-(49+0.1*p)*x1+9*x2+x1*x3+(49+0.1*p)*y1-9*y2-y1*y3;%-16*y;
f(3)=-2.5*x3+4*x1*x1;
f(4)=10*(y2-y1);
f(5)=40*y1-y1*y3;
f(6)=-2.5*y3+4*y1*y1;