function f=sys_rhs(xx,par)

% T
x = xx(1,1);
xd = xx(2,1);
xl = xx(1,2);
xld = xx(2,2);
e = 1;                        % for double-hopf detuning
k = 6.8915;
% e = .01;
% k = 6.891601795508331;

f(1,1) = xd;
f(2,1) = -(4/k)*xd - 4*x - (10/k)*xld + (e/k)*x.^3;

return;
