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+//caption:determine_close_loop_stability
+//example 12_33
+//page 550
+s=%s;
+g=(720*(s+1.25))/(s*(s+10)*(s^2+2*s+9));
+G=syslin('c',g)
+fmin=0.1; 
+fmax=100; 
+bode(G, fmin, fmax) 
+[gm,freqGM]=g_margin(G);
+[pm,freqPM]=p_margin(G);
+show_margins(G);
+disp(gm,"gain_margin=");
+disp((freqGM*2*%pi),"gain_margin_freq=");
+disp(pm,"phase_margin=");
+disp((freqPM*2*%pi),"phase_margin_freq=");
+show_margins(G);
+disp("since gain and phase margin are both negative so system is unstable")