e8p20.m

% Example 8.20  
t0 = [0.75 0.499 0]; w = 0.3:0.1:4;
for k = 1:3
   [re,im,w] = nyquist([1],[1 2 1 0],w);
     Dl = exp(j*t0(k)*w);
     Gw = (re+j*im) .* Dl;
     Greal = real(Gw); Gimag = imag(Gw);
       plot(Greal,Gimag)
       title('Nyquist Diagram'); xlabel('Re G(jw)');
       ylabel('Im G(jw)'); grid; hold on
end
hold off