The program is primary added perplexity computing method based on Arnim Bleier's Java Gibbs sampler for the HDP.

Readme content in Arnim Bleier's program:

This is a Java 1.6 implementation of a Chinese Restaurant Franchise Gibbs Sampler, a Bayesian Nonparametric Topic model fitter.

The algorithm for the Chinese Restaurant Franchise Sampler is described in:

Hierarchical Bayesian Nonparametric Models with Applications. 
Y.W. Teh and M.I. Jordan. Bayesian Nonparametrics, 2010. Cambridge University Press.
http://www.gatsby.ucl.ac.uk/~ywteh/research/npbayes/TehJor2010a.pdf

The closest related software is Chong Wang's C implementation Hierarchical Dirichlet processes for text

• http://www.gatsby.ucl.ac.uk/~ywteh/research/software.html (by Yee Whye Teh) MATLAB and C
• http://www.arbylon.net/resources.html (by Gregor Heinrich) Java

under the GNU Lesser General Public License