close all
 clear all;
 N=60;
 c=1500;
 f=1500;
 a=2*pi/N;
 lamda=c/f;
r=lamda/0.4;
 x=0:pi/180:pi;
 a=0;
 b=0;
 theter=[0,pi/6];
 for j=1:2
 for i=1:60
     derta=r/c*[cos(x-(i-1)*a)-cos(theter(j)-(i-1)*a)];
     a=a+cos(2*pi*f.*derta);
     b=b+sin(2*pi*f.*derta);
 end
 R=sqrt(a.^2+b.^2)/N;
 if theter==0
    subplot(211);plot(x,abs(R));title('相移')
 else
         subplot(212);plot(x,abs(R));title('有像一')
      end
  end