Gaussian mixture distribution plot

I'm trying to bild a gaussian mixture distribution. I'm quite new on Matlab, but I think the script is ok. I'm not able to plot my distribution. Here you can find what I have. Many thanks for your answers, cheers

%quadmodal mixture
mu=[30 0 0 0; 22 0 0 0;12 0 0 0;4 0 0 0]; 
sigma=cat(3,[9^2 0 0 0;0 6.6^2 0 0;0 0 3.6^2 0;0 0 0 1.2^2],[1 0 0 0;0 1 0 0;0 0 1 0;0 0 0 1],[1 0 0 0;0 1 0 0;0 0 1 0;0 0 0 1],[1 0 0 0;0 1 0 0;0 0 1 0;0 0 0 1]);
p=ones(1,4)/4;
obj = gmdistribution(mu,sigma,p);
ezsurf(@(x,y)pdf(obj,[x y]),[-25 25],[-25 25])

[zepp]

your mixture distribution has four dimensions, so you cannot plot that using ezsurf. Are you sure you have initialised the mu and sigma values correctly? Or is it just a 1 dimensional 4 component Gaussian distribution?