function [xdot]=lorenz(t,x)
a=10;
b=28;
c=8/3;
xdot=zeros(3,1);

xdot(1) = a *(x(2)-x(1));
xdot(2) = x(1)  *(b-x(3)) - x(2);
xdot(3) = x(1)* x(2) - c *x(3);