[mlpack-svn] [MLPACK] #238: Fix volume regularization in DET

[MLPACK Trac]

#238: Fix volume regularization in DET
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 Reporter:  rcurtin  |        Owner:                                      
     Type:  defect   |       Status:  new                                 
 Priority:  minor    |    Milestone:                                      
Component:  mlpack   |     Keywords:  volume regularization, det, logspace
 Blocking:           |   Blocked By:                                      
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 When switching to using log-space, I did not take the time to figure out
 how to have the volume regularized calculation of alpha work in logspace.
 Currently the code looks like:

 {{{
 if (useVolReg)
 {
   // This is incorrect.
   gT = alphaUpper; // / (subtreeLeavesVTInv - vTInv);
 }
 }}}

 In normal space, the expression in the denominator is the sum of all the
 inverse volumes of the leaves, with the inverse volume of the node
 subtracted from it.  How to do this in logspace is slightly less clear; we
 want to avoid non-logspace representation of volumes.

-- 
Ticket URL: <http://trac.research.cc.gatech.edu/fastlab/ticket/238>
MLPACK <www.fast-lab.org>
MLPACK is an intuitive, fast, and scalable C++ machine learning library developed by the FASTLAB at Georgia Tech under Dr. Alex Gray.