Merge pull request #1545 from Wenhao-H/master

CF: small fixes in returning normalization object

src/mlpack/methods/cf/cf.hpp

@@ -179,6 +179,9 @@ class CFType
   //! Get the cleaned data matrix.
   const arma::sp_mat& CleanedData() const { return cleanedData; }
 
+  //! Get the normalization object.
+  const NormalizationType& Normalization() const { return normalization; }
+
   /**
    * Generates the given number of recommendations for all users.
    *

src/mlpack/methods/cf/normalization/combined_normalization.hpp

@@ -93,7 +93,7 @@ class CombinedNormalization
   /**
    * Return normalizations tuple.
    */
-  TupleType Normalizations() const
+  const TupleType& Normalizations() const
   {
     return normalizations;
   }