problems with the eigenvalues

I have computed the eigenvalues of a 8*8 matrix, but I want to obtain the three largest eigenvalue of the matrix. I don't know how to do it. Can you help me with it and give me some suggestions. Thank you in advance! Regards, Song

Answer 1

[bym]

eig returns the eigenvalues already sorted

[vec,val]=eig(rand(8));
diag(val)

[John D'Errico]

Actually, there is no certainty that they are sorted. They will be ROUGHLY sorted because of the method used, but the exact order may vary slightly.

[Walter Roberson]

Right, they are not necessarily sorted, and if you look through old messages you can find complaints about changes in the order. I'm not certain but I seem to recall some people indicating that they got a different order with MATLAB Compiler.