From d83868fdbbc6a3e9f67c966a190d517a2fb7f9f7 Mon Sep 17 00:00:00 2001
From: paboyle <paboyle@ph.ed.ac.uk>
Date: Wed, 25 Oct 2017 23:47:10 +0100
Subject: [PATCH] Identity linear op added -- useful in circumstances where a
 linear op may or may not be needed. Supply a trivial one if not needed

---
 lib/algorithms/LinearOperator.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/algorithms/LinearOperator.h b/lib/algorithms/LinearOperator.h
index 0d32cc15..2a68a7b9 100644
--- a/lib/algorithms/LinearOperator.h
+++ b/lib/algorithms/LinearOperator.h
@@ -346,6 +346,13 @@ namespace Grid {
       virtual void operator() (const Field &in, Field &out) = 0;
     };
 
+    template<class Field> class IdentityLinearFunction : public LinearFunction<Field> {
+    public:
+      void operator() (const Field &in, Field &out){
+	out = in;
+      };
+    };
+
 
     /////////////////////////////////////////////////////////////
     // Base classes for Multishift solvers for operators