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diff --git a/257/CH11/EX11.9/example_11_9.sce b/257/CH11/EX11.9/example_11_9.sce
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+s=poly(0,'s'); 
+F=syslin('c',[(s^2)/((1+0.2*s)*(0.02*s+1))])                  //without k
+
+fmin=0.1;                                        //Min freq in Hz
+fmax=20;                                          //Max freq in Hz
+
+scf(1);clf;
+bode(F,fmin,fmax);                                //Plots frequency response of open-loop system in Bode diagram
+
+[GainMargin,freqGM]=g_margin(F)                 //Calculates gain margin [dB] and corresponding frequency [Hz]
+disp(GainMargin,"GM=")
+disp(freqGM*2*3.14,"omegaPC=")
+
+[PhaseMargin,freqPM]=p_margin(F)                //Calculates phase [deg] and corresponding freq [Hz] of phase margin
+disp(PhaseMargin,"PM=")
+disp(freqPM*2*3.14,"omegaGC")
+
+show_margins(F)                                //display gain and phase margin and associated crossover frequencies
+
+// TO FIND VALUE OF K
+
+// at omega=5, the point on the plot without k 28dB away from 0dB line.
+k1=10^(-28/20)                                      // 20*log(k1)=-28
+disp(k1,"k for omegaGC=5 is ")