1 files changed, 25 insertions, 0 deletions
diff --git a/257/CH9/EX9.25/example_9_25.sce b/257/CH9/EX9.25/example_9_25.sce
new file mode 100644
index 000000000..17b53b06b
--- /dev/null
+++ b/257/CH9/EX9.25/example_9_25.sce
@@ -0,0 +1,25 @@
+s=%s
+sys=syslin('c',k/(s*(s+4)*(s+2)))
+evans(sys)
+
+
+//values of k
+
+[Ki,s]=kpure(sys) 
+disp("k should be less than")
+disp(Ki)
+
+//frequency of oscillations
+s=%s
+P=s^3+6*s^2+8*s+Ki
+routh=routh_t(P)
+disp(routh)
+disp("frequency of oscillations is")
+ disp(sqrt((roots(routh(2,:)))))
+ 
+ //damping ratio is 0.5 given
+// cos inverse of 0.5 is 60  degrees. from the root locus, the 60 degree line crosses the locus at (-0.75+j*1.25)
+
+f=(-0.75+%i*1.25)
+disp("k for damping ratio 0.5 is")
+disp(abs(f*(f+4)*(f+2)))
+\ No newline at end of file