Add empty Serialize() methods to initialization policies.

src/mlpack/methods/amf/init_rules/average_init.hpp

@@ -68,6 +68,10 @@ class AverageInitialization
     W = W + avgV;
     H = H + avgV;
   }
+
+  //! Serialize the object (in this case, there is nothing to do).
+  template<typename Archive>
+  void Serialize(Archive& /* ar */, const unsigned int /* version */) { }
 };
 
 } // namespace amf

src/mlpack/methods/amf/init_rules/random_acol_init.hpp

@@ -76,6 +76,10 @@ class RandomAcolInitialization
     // Initialize H to random values.
     H.randu(r, m);
   }
+
+  //! Serialize the object (in this case, there is nothing to serialize).
+  template<typename Archive>
+  void Serialize(Archive& /* ar */, const unsigned int /* version */) { }
 };
 
 } // namespace amf

src/mlpack/methods/amf/init_rules/random_init.hpp

@@ -45,6 +45,10 @@ class RandomInitialization
     W.randu(n, r);
     H.randu(r, m);
   }
+
+  //! Serialize the object (in this case, there is nothing to serialize).
+  template<typename Archive>
+  void Serialize(Archive& /* ar */, const unsigned int /* version */) { }
 };
 
 } // namespace amf