how do I draw the cluster boundaries in a scatter plot?

I have a scatter plot of three clusters. How can I represent them by showing the cluster boundaries rather than using colours for the different clusters? I would like to draw circles (or ellipses) around each cluster. These clusters were created using a mixture model and I have also created the gmdistribution object of the model if that can be useful.

Thanks

Answer 1

[Image Analyst]

Maybe adapt this http://blogs.mathworks.com/pick/2014/01/03/fit-a-sphere/ ??

Answer 2

[Adam Cutbill]

You can also use the convex hull operation if you're more concerned with capturing the boundary than making sure it is a ellipse.(<http://www.mathworks.com/help/matlab/math/convex-hulls.html>)