function dxdt = kepler_ode2X(t,X)
% assume 'Y' is a vector of form y = [ x ; y ; z]
global rho sigma beta
%sigma = 10;

x = X(1);
y = X(2);
z = X(3);

dxdt = sigma.*(y - x);

dxdt = [dxdt;0;0];


        
