//Chapter-2,Example2_6_3,pg 2-33

wavelength=5890*10^-10                                    //wavelength of light 

d_wavelength=6*10^-10

m=2                                                //for second order 

N=wavelength/(d_wavelength*m)

W=N/500                                          //as there are 500 lines/cm
 
printf('\n The width of grating is W = %.3f cm',W)