From 0e04d88628a9c899cc33e9bdc45446bb4dad99f3 Mon Sep 17 00:00:00 2001
From: Hrvoje Jasak <h.jasak@wikki.co.uk>
Date: Wed, 5 Apr 2017 11:08:42 +0100
Subject: [PATCH] Added zero CoeffField

---
 src/foam/fields/CoeffField/CoeffField.C |  4 ++++
 src/foam/fields/CoeffField/CoeffField.H | 24 ++++++++++++++++++------
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/src/foam/fields/CoeffField/CoeffField.C b/src/foam/fields/CoeffField/CoeffField.C
index 6fb7a6201..ea3233901 100644
--- a/src/foam/fields/CoeffField/CoeffField.C
+++ b/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  * * * * * * * * * * * //
 
diff --git a/src/foam/fields/CoeffField/CoeffField.H b/src/foam/fields/CoeffField/CoeffField.H
index 159e73c38..a46ee682d 100644
--- a/src/foam/fields/CoeffField/CoeffField.H
+++ b/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
 
@@ -138,12 +151,8 @@ public:
         tmp<CoeffField<Type> > clone() const;
 
 
-    // Destructor
-
-        ~CoeffField();
-
-        //- Clear data
-        void clear();
+    //- Destructor
+    ~CoeffField();
 
 
     // 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