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+//Introduction to Fiber Optics by A. Ghatak and K. Thyagarajan, Cambridge, New Delhi, 1999
+//Example 21.9
+//OS=Windows XP sp3
+//Scilab version 5.5.2
+clc;
+clear;
+//given
+//Since the peak reflectivity of fiber is 0.85,
+R=0.85;//Reflection coefficient of fiber
+L=1e-2;//Length of interaction in m
+lambda0=1.55e-6;//Central wavelength in m
+neff=1.46;//Corresponding value of effective index in LP01 mode
+
+//Now, (tanh(k*L))^2=R
+//Rearranging terms, we get:
+k=atanh(sqrt(R))/L;//Corresponding coupling coefficient in m^(-1)
+mprintf("\n k=%.3f m^(-1)",k);//The answer provided in the textbook is wrong
+
+//Let A be the perturbation of length in m
+A=lambda0/(2*neff);
+mprintf("\n A=%.2f nm",A/1e-9);//Division by 10^(-9) to convert into nm
+//The answers vary due to round off error
+
+DeltaLambda=lambda0^2/(%pi*neff*L)*sqrt((k*L)^2+(%pi)^2);//Corresponding bandwidth in m
+mprintf("\n DeltaLambda=%.2f nm",DeltaLambda/1e-9);//Division by 10^(-9) to convert into nm
+//The answer provided in the textbook is wrong