The biggest change in the 4.0 release of popsom is the inclusion of a vectorized version of the stochastic SOM training algorithm. This new training algorithm runs up to 10 times faster than the batch algorithm and between 50 to 100 times faster than the traditional stochastic training algorithm. Of course the precise numbers depend strongly on the kind of problem you are working on.

The SOM quality reporting function have been made consistent with our recent publications: see

8/12/16, Kingston, RI, USA