For a matrix with 600 rows and 500 columns, this function was quite slow. I would recommend another method. The 'active set' and 'block pivot' methods by the same author are both much faster. Those codes are:
http://www.mathworks.com/matlabcentral/fileexchange/10908-active-set-algorithm
and
http://www.mathworks.com/matlabcentral/fileexchange/8157-nnls