matlab 二维坐标转换成极坐标并画图显示

[theta,rho]=cart2pol(y,x);           

th(1,youxiaogeshu)=theta;
dis(1,youxiaogeshu)=rho;
plot(rho,theta,'r+');text(rho,theta,num2str(id)) ;
polar(theta,rho,'ro');