diff --git a/src/multi_array_operation.cc b/src/multi_array_operation.cc
index 84ccfa5..9d4d275 100644
--- a/src/multi_array_operation.cc
+++ b/src/multi_array_operation.cc
@@ -161,6 +161,15 @@ namespace MultiArrayTools
     	return Operation<T,std::divides<T>,OperationClass,Second>(*mOc, in);
     }
 
+    template <typename T, class OperationClass>
+    template <class IndexType>
+    auto OperationTemplate<T,OperationClass>::c(std::shared_ptr<IndexType>& ind) const
+	-> Contraction<T,OperationClass,IndexType>
+    {
+	return Contraction<T,OperationClass,IndexType>(*mOc, ind);
+    }
+
+    
     /*************************
      *   OperationMaster     *
      *************************/
diff --git a/src/multi_array_operation.h b/src/multi_array_operation.h
index 7f3db9c..6fa7a48 100644
--- a/src/multi_array_operation.h
+++ b/src/multi_array_operation.h
@@ -108,6 +108,10 @@ namespace MultiArrayTools
 	template <class Second>
 	auto operator/(const Second& in) const
 	    -> Operation<T,std::divides<T>,OperationClass,Second>;
+
+	template <class IndexType>
+	auto c(std::shared_ptr<IndexType>& ind) const
+	    -> Contraction<T,OperationClass,IndexType>;
 	
     private:
 	OperationClass* mOc;
@@ -223,15 +227,15 @@ namespace MultiArrayTools
 	mutable BlockResult<T> mRes;
     };
 
-    template <typename T, class Op>
+    template <typename T, class Op, class IndexType>
     class Contraction : public OperationTemplate<T,Contraction<T,Op> >
     {
     public:
 
 	typedef T value_type;
-	typedef OperationTemplate<T,Contraction<T,Op> > OT;
-
-	Contraction(const Op& op);
+	typedef OperationTemplate<T,Contraction<T,Op,IndexType> > OT;
+	
+	Contraction(const Op& op, std::shared_ptr<IndexType> ind);
 	
 	const BlockResult<T>& get() const;
 
@@ -241,8 +245,8 @@ namespace MultiArrayTools
     protected:
 
 	const Op& mOp;
+	std::shared_ptr<IndexType> mInd;
 	mutable BlockResult<T> mRes;
-	
     };
     
 }