add SumColumnElements function to ComputationNetwork

Change Sum function to SumElements in ComputationNetwork

MachineLearning/CNTK/ComputationNetwork.h

@@ -2122,7 +2122,7 @@ public:
         return newNode;
     }
 
-    ComputationNodePtr Sum(const ComputationNodePtr a, const std::wstring nodeName = L"")
+    ComputationNodePtr SumElements(const ComputationNodePtr a, const std::wstring nodeName = L"")
     {
         ComputationNodePtr newNode(new SumElementsNode<ElemType>(m_deviceId, nodeName));
         newNode->AttachInputs(a);
@@ -2130,6 +2130,13 @@ public:
         return newNode;
     }
 
+    ComputationNodePtr SumColumnElements(const ComputationNodePtr a, const std::wstring nodeName = L"")
+    {
+        ComputationNodePtr newNode(new SumColumnElementsNode<ElemType>(m_deviceId, nodeName));
+        newNode->AttachInputs(a);
+        AddNodeToNet(newNode);
+        return newNode;
+    }
     ComputationNodePtr Scale(const ComputationNodePtr scalar,
                              const ComputationNodePtr matrix,
                              const std::wstring nodeName = L"")

MachineLearning/CNTK/SynchronousExecutionEngine.h

@@ -316,7 +316,7 @@ public:
                  cnNodeType == FutureValueNode<ElemType>::TypeName())
         {
             if (parameter.size() <2 || parameter.size() >3)
-                RuntimeError("PastValue or FutureValue should have two to three fixed parameters. Usage: PastValue(rows, [cols], m, [timeStep=1, defaultPastValue=0.1]).");
+                RuntimeError("PastValue or FutureValue should have two to three fixed parameters. Usage: PastValue(rows, [cols], m, [timeStep=1, defaultHiddenActivity=0.1]).");
 
             nodeParamCount = 1;
             nodeParamStart = parameter.size() > 2?2:1;