From 5c4f0c3f1b79e5cab12adda2b64c2722013956fa Mon Sep 17 00:00:00 2001
From: Christian Zimmermann <christian.zimmermann@ur.de>
Date: Thu, 19 Jul 2018 13:00:34 +0200
Subject: [PATCH] some operation utilities

---
 src/include/multi_array_operation.h | 65 +++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

diff --git a/src/include/multi_array_operation.h b/src/include/multi_array_operation.h
index e4b65f0..b3754ae 100644
--- a/src/include/multi_array_operation.h
+++ b/src/include/multi_array_operation.h
@@ -305,6 +305,71 @@ namespace MultiArrayTools
     {
 	return Operation<typename OpFunction::value_type,OpFunction,Ops...>(ops...);
     }
+
+    template <typename T, class OperationClass>
+    auto operator+(const T& a, const OperationBase<T,OperationClass>& b)
+	-> Operation<T,plus<T>,OperationValue<T>,OperationClass>
+    {
+	OperationValue<T> v(a);
+	return Operation<T,plus<T>,OperationValue<T>,OperationClass>(v, b.THIS());
+    }
+
+    template <typename T, class OperationClass>
+    auto operator-(const T& a, const OperationBase<T,OperationClass>& b)
+	-> Operation<T,minus<T>,OperationValue<T>,OperationClass>
+    {
+	OperationValue<T> v(a);
+	return Operation<T,minus<T>,OperationValue<T>,OperationClass>(v, b.THIS());
+    }
+
+    template <typename T, class OperationClass>
+    auto operator*(const T& a, const OperationBase<T,OperationClass>& b)
+	-> Operation<T,multiplies<T>,OperationValue<T>,OperationClass>
+    {
+	OperationValue<T> v(a);
+	return Operation<T,multiplies<T>,OperationValue<T>,OperationClass>(v, b.THIS());
+    }
+
+    template <typename T, class OperationClass>
+    auto operator/(const T& a, const OperationBase<T,OperationClass>& b)
+	-> Operation<T,divides<T>,OperationValue<T>,OperationClass>
+    {
+	OperationValue<T> v(a);
+	return Operation<T,divides<T>,OperationValue<T>,OperationClass>(v, b.THIS());
+    }
+
+    template <typename T, class OperationClass>
+    auto operator+(const OperationBase<T,OperationClass>& a, const T& b)
+	-> Operation<T,plus<T>,OperationClass,OperationValue<T> >
+    {
+	OperationValue<T> v(b);
+	return Operation<T,plus<T>,OperationClass,OperationValue<T> >(a.THIS(), v);
+    }
+
+    template <typename T, class OperationClass>
+    auto operator-(const OperationBase<T,OperationClass>& a, const T& b)
+	-> Operation<T,minus<T>,OperationClass,OperationValue<T> >
+    {
+	OperationValue<T> v(b);
+	return Operation<T,minus<T>,OperationClass,OperationValue<T> >(a.THIS(), v);
+    }
+
+    template <typename T, class OperationClass>
+    auto operator*(const OperationBase<T,OperationClass>& a, const T& b)
+	-> Operation<T,multiplies<T>,OperationClass,OperationValue<T> >
+    {
+	OperationValue<T> v(b);
+	return Operation<T,multiplies<T>,OperationClass,OperationValue<T> >(a.THIS(), v);
+    }
+
+    template <typename T, class OperationClass>
+    auto operator/(const OperationBase<T,OperationClass>& a, const T& b)
+	-> Operation<T,divides<T>,OperationClass,OperationValue<T> >
+    {
+	OperationValue<T> v(b);
+	return Operation<T,divides<T>,OperationClass,OperationValue<T> >(a.THIS(), v);
+    }
+
     
     template <typename T, class Op, class IndexType>
     class Contraction : public OperationTemplate<T,Contraction<T,Op,IndexType> >