function plot_astrology(a,b)
%畫出星座圖
%figure(c)
subplot(1,1,1)
plot(a,b,'+');
axis([-5 5 -5 5]);
line([-5,5],[0,0],'LineWidth',3,'Color','red');
line([0,0],[-5,5],'LineWidth',3,'Color','red');
title('QAM星座圖');