[mlpack-git] master, mlpack-1.0.x: Make a note that this set of update rules often creates lots of NaNs when sparse matrices are used. (6e9ef0e)

[gitdub at big.cc.gt.atl.ga.us]

Repository : https://github.com/mlpack/mlpack

On branches: master,mlpack-1.0.x
Link       : https://github.com/mlpack/mlpack/compare/904762495c039e345beba14c1142fd719b3bd50e...f94823c800ad6f7266995c700b1b630d5ffdcf40

>---------------------------------------------------------------

commit 6e9ef0e95f2e18956f60bac3897667c76e49df07
Author: Ryan Curtin <ryan at ratml.org>
Date:   Mon Jun 23 21:39:03 2014 +0000

    Make a note that this set of update rules often creates lots of NaNs when sparse
    matrices are used.


>---------------------------------------------------------------

6e9ef0e95f2e18956f60bac3897667c76e49df07
 src/mlpack/methods/amf/update_rules/nmf_mult_div.hpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/mlpack/methods/amf/update_rules/nmf_mult_div.hpp b/src/mlpack/methods/amf/update_rules/nmf_mult_div.hpp
index b4d7037..3b17f13 100644
--- a/src/mlpack/methods/amf/update_rules/nmf_mult_div.hpp
+++ b/src/mlpack/methods/amf/update_rules/nmf_mult_div.hpp
@@ -9,6 +9,10 @@
  * \f$ \sum_i \sum_j (V_{ij} log\frac{V_{ij}}{(WH)_{ij}}-V_{ij}+(WH)_{ij}) \f$is
  * non-increasing between subsequent iterations. Both of the update rules
  * for W and H are defined in this file.
+ *
+ * This set of update rules is not meant to work with sparse matrices.  Using
+ * sparse matrices often causes NaNs in the output, so other choices of update
+ * rules are better in that situation.
  */
 #ifndef __MLPACK_METHODS_LMF_UPDATE_RULES_NMF_MULT_DIV_HPP
 #define __MLPACK_METHODS_LMF_UPDATE_RULES_NMF_MULT_DIV_HPP
@@ -18,7 +22,6 @@
 namespace mlpack {
 namespace amf {
 
-
 class NMFMultiplicativeDivergenceUpdate
 {
  public: