Normalized Mutual Information

Fully vectorized implementation NMI. NMI is often used for evaluating clustering results.

Normalized mutual information is often used for evaluating clustering results, information retrieval, feature selection etc. This is a optimized implementation of the function which has no for loops.
This function is now a part of the PRML toolbox (http://www.mathworks.com/matlabcentral/fileexchange/55826-pattern-recognition-and-machine-learning-toolbox).