matlab画图，在图中标出字母

point=[1.8 3.1 4.3 3.5 2; 3.4 4.9 3 1.1 1.8];centroid=[2.94; 2.84];UnknownNode=[3.14; 3.04];plot(point(1,:),point(2,:),'b^')hold onplot(centroid(1),centroid(2),'ro')hold onplot(UnknownNode(1),UnknownNode(2),'m*');hold onM=['A_1','B','C','D','E']text(point(1,:)+0.1,point(2,:)+0.1,[M(:)],'color','b')hold ontext(UnknownNode(1,1)+0.1,UnknownNode(2,1)+0.1,'S','color','m')hold ontext(centroid(1,1)+0.1,centroid(2,1)-0.1,'Centroid','color','r')hold onxlim([0,6]);ylim([0,6]);axis offlegend('BeaconNode','Centroid','UnknownNode');