function [] = Nyquist2(Gw, Mm)

   Gwp = unwrap(angle(Gw))*180/pi;
   Gwm = 20*log10(abs(Gw));

% M-Circle
   phase = [0:0.01:1]' * 2*pi;
   Mcl = Mm * exp(j*phase);
   Mol = Mcl ./ (1 - Mcl);

   plot(real(Gw), imag(Gw), 'b', real(Mol), imag(Mol),'r',-1,0,'r+');
   xlabel('real');
   ylabel('imag');
   xlim([-2,0.5]);
   ylim([-2,0.5]);
   end