ordering of eigenvalues in matlab.
Steven Lord, from Matlab Tech Support, says the "EIG()" function calls LAPACK.
http://www.mathworks.com/matlabcentral/newsreader/view_thread/156868
The ordering of eigenvalues is determined in LAPACK and is not set by Matlab. Someone else already ran into this, and wrote a function to sort eigenvalues and associated eigenvectors:
http://www.mathworks.com/matlabcentral/fileexchange/18904-sort-eigenvectors-eigenvalues
I then incorporated this sorting into eigenvalue correlation analysis.