//chapter 7 example 2// clc clear //longitudnal displacement=S,numerical aperure=NA,core radius=a,coupling efficiency=ns1.critical angle=Am// NA=0.2; Am=asind(NA);//in deg// printf("\n critical angle=%f deg\n",Am) a=25*(10^-6);//in mts// S=2.5*(10^-6);//in mts// ns1=((a/(a+(S*tand(Am))))^2)*100; printf("\n coupling efficiency=%f percent\n",ns1)