theta = linspace(0,2*pi,100);


lam = (exp(3*i*theta) - exp(2*i*theta))./(23/12*exp(2*i*theta) - ...
                                          16/12*exp(i*theta) + 5/12);

plot(lam);
axis('equal');
axis([-3,3,-3,3]);
grid on;
xlabel('\lambda_{r}\Delta t');
ylabel('\lambda_{i}\Delta t');