Gives the parameters of the ellipse - output from the ellipsoidhull functon in cluster.
Details
Routine adapted from a suggestion made on CrossValidated: http://stats.stackexchange.com/questions/9898/how-to-plot-an-ellipse-from-eigenvalues-and-eigenvectors-in-r
References
Maechler, M., Rousseeuw, P., Struyf, A., Hubert, M., Hornik, K.(2013).
cluster: Cluster Analysis Basics and Extensions. R package version 1.14.4.