data = rand(100,2) ;
plot(data(:,1),data(:,2),'.r') ;
%%draw ellipse
x = data(:,1) ; y = data(:,2) ;
x0 = min(x) ; x1 = max(x) ;
y0 = min(y) ; y1 = max(y) ;
a=abs(x1-x0) ; % horizontal radius
b=abs(y1-y0); % vertical radius
% x0,y0 ellipse centre coordinates
x0=mean(x);
y0=mean(y);
t=-pi:0.01:pi;
xe=x0+a*cos(t);
ye=y0+b*sin(t);
hold on
plot(xe,ye,'b')
