script for matlab

gistfile1.txt

a1 = 6.82;
a2 = 4.93;
a3 = -6.515;
a4 = -5.382;
 
system = tf(1, [1 a1 a2 a3 a4]);
 
figure;
nyquist(system);
 
figure;
bode(system);
 
figure;
impulse(system);
 
figure
Re = [];
Im = [];
 
for w=0:0.01:1.1
  Njw = ((w*i)^4) + a1*((w*i)^3) + a2*((w*i)^2) + a3*(w*i) + a4;
  Re1 = real(Njw);
  Im1 = imag(Njw);
  Re = [Re,Re1];
  Im = [Im,Im1];
end
 
ax = axes;
plot(Re, Im);
set(ax, 'XGrid', 'on', 'YGrid', 'on');