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Topic: Draw ellipse for multivariate data
Replies: 0

 eren eren Posts: 2 Registered: 12/12/12
Draw ellipse for multivariate data
Posted: Dec 12, 2012 4:05 PM

i want to draw ellipse for multivariate data.
here is my wish;
i have some random numbers x which is

mu=zeros(1,p) % p is dimension
var=eye(p) % p is dimension
x=mvnrnd(mu,var,n)

and i estimate the location and shape parameter of this data with MCD method. method is not important for you because i don't have any problem. And then

i want draw an ellipsoid with center estimated location parameter and its' border is chi-squre with p degrees of freedom and alfa=0.05. in theory inequality is;

1-) (x-mu)'*inv(var)*(x-mu)<= chi2inv(p,alfa) x element of R1
2-) chi2inv(p,alfa)<(x-mu)'*inv(var)*(x-mu)<= chi2inv(p,sigma) x element of R2
3-) (x-mu)'*inv(var)*(x-mu)> chi2inv(p,sigma) x element of R3

and i want to draw R1,R2 and R3 ellipses. These are three nested ellipses.

How can i do this?