Added zero CoeffField

src/foam/fields/CoeffField/CoeffField.C

@@ -31,6 +31,10 @@ License
 template<class Type>
 const char* const Foam::CoeffField<Type>::typeName("CoeffField");
 
+template<class Type>
+const Foam::CoeffField<Type> Foam::CoeffField<Type>::zero(0);
+
+
 
 // * * * * * * * * * * * * * Private Member Functions  * * * * * * * * * * * //
 

src/foam/fields/CoeffField/CoeffField.H

@@ -122,6 +122,19 @@ public:
 
         static const char* const typeName;
 
+        //- Empty field
+        static const CoeffField<Type> zero;
+
+
+    // Static Member Functions
+
+        //- Return a null field
+        inline static const CoeffField<Type>& null()
+        {
+            return zero;
+        }
+
+
 
     // Constructors
 
@@ -138,13 +151,9 @@ public:
         tmp<CoeffField<Type> > clone() const;
 
 
-    // Destructor
+    //- Destructor
-
     ~CoeffField();
 
-        //- Clear data
-        void clear();
-
 
     // Member functions
 
@@ -163,6 +172,9 @@ public:
         //- Return the field transpose
         tmp<CoeffField<Type> > transpose() const;
 
+        //- Clear data
+        void clear();
+
 
         // Return as typed.  Fails when asked for the incorrect type