function xdot = rhs(t,x)
  xdot = zeros(3,1);
 
%define parameter values
  sig = 10;
  rho = 29;
  bet = 8/3;
 
% right hand sides of each of 3 equations

 xdot(1) = sig*(x(2)-x(1));
  xdot(2) = rho*x(1)-x(2)-x(1)*x(3);
  xdot(3) = x(1)*x(2)-bet*x(3);
