//Chapter-2,Example2_4_11,pg 2-28

m=1                                                  //first ordr spectrum

wavelength=5790*10^-10                                       //wavelength of light 

angle=19.994                                    //angle of diffraction

N=2.54*sind(angle)/(m*wavelength*100)

printf('\nNumber of lines per 2.54 cm  is  N = %.0f lines',N)