diff --git a/src/include/base/types.h b/src/include/base/types.h
index 5f3e658..616a652 100644
--- a/src/include/base/types.h
+++ b/src/include/base/types.h
@@ -215,7 +215,14 @@ namespace CNORXZ
     
     template <typename T>
     using Vector = std::vector<T,Allocator<T>>;
-    
+
+    template <typename T, SizeT N, bool Static>
+    struct Container
+    { typedef Vector<T> type; };
+
+    template <typename T, SizeT N>
+    struct Container<T,N,true>
+    { typedef Arr<T,N> type; };
 }
 
 #endif
diff --git a/src/include/operation/op_types.cc.h b/src/include/operation/op_types.cc.h
index eb07e85..01a1ac9 100644
--- a/src/include/operation/op_types.cc.h
+++ b/src/include/operation/op_types.cc.h
@@ -18,7 +18,7 @@ namespace CNORXZ
     template <class F, class IndexT>
     constexpr decltype(auto) COpInterface<OpT>::c(F&& f, const Sptr<IndexT>& ind) const
     {
-	return mkContraction(std::forward<F>(f), THIS(), ind);
+	return mkContraction(std::forward<F>(f), THIS().r(), ind);
     }
 
     template <class OpT>
@@ -33,7 +33,7 @@ namespace CNORXZ
     template <class F, class... Args>
     constexpr decltype(auto) COpInterface<OpT>::o(F&& f, Args&&... args) const
     {
-        return Operation<F,OpT,Args...>(std::forward<F>(f), THIS(), args...);
+	return mkOperation(std::forward<F>(f), THIS().r(), args...);
     }
 
     
@@ -45,7 +45,7 @@ namespace CNORXZ
     template <class IndexT, class F, class... Args>
     constexpr decltype(auto) OpInterface<OpT>::ax(const Sptr<IndexT>& ind, F&& f, const Args&... args)
     {
-	return ind->ifor( Operation<F,OpT,Args...>(f, THIS(), args...), NoF {} );
+	return ind->ifor( mkOperation(f, OI::THIS().r(), args...), NoF {} );
     }
 
     template <class OpT>
@@ -126,11 +126,8 @@ namespace CNORXZ
     constexpr OpCont<T,IndexT>& OpCont<T,IndexT>::init(const Sptr<IndexT>& ind)
     {
 	mIndex = ind;
-	if(not mC){
-	    mC = std::make_shared<Vector<T>>(mIndex->pmax().val());
-	}
-	else if(mC->size() != mIndex->pmax().val()){
-	    mC->resize(mIndex->pmax().val());
+	if(mC.size() != mIndex->pmax().val()){
+	    mC.resize(mIndex->pmax().val());
 	}
 	return *this;
     }
@@ -140,12 +137,24 @@ namespace CNORXZ
 						       const Vector<T>& c)
     {
 	init(ind);
-	CXZ_ASSERT(c.size() == mC->size(),
-		   "size-mismatch: expected " << mC->size() << ", got " << c.size());
-	std::transform(c.begin(), c.end(), mC->begin(), [](const auto& x) { return x; } );
+	CXZ_ASSERT(c.size() == mC.size(),
+		   "size-mismatch: expected " << mC.size() << ", got " << c.size());
+	std::transform(c.begin(), c.end(), mC.begin(), [](const auto& x) { return x; } );
 	return *this;
     }
 
+    template <typename T, class IndexT>
+    constexpr decltype(auto) OpCont<T,IndexT>::r()
+    {
+	return OpRoot<T,IndexT>(data(), mIndex);
+    }
+
+    template <typename T, class IndexT>
+    constexpr decltype(auto) OpCont<T,IndexT>::r() const
+    {
+	return COpRoot<T,IndexT>(data(), mIndex);
+    }
+
     template <typename T, class IndexT>
     template <class Op>
     constexpr OpCont<T,IndexT>& OpCont<T,IndexT>::operator=(const Op& o)
@@ -175,23 +184,23 @@ namespace CNORXZ
     {
 	if constexpr(is_epos_type<PosT>::value){
 	    if constexpr(pos_type_is_consecutive<PosT>::value){
-		return vreg(mC->data(),pos);
+		return vreg(mC.data(),pos);
 	    }
 	    else {
 		// non-consecutive data cannot be directly accessed
 		// so there is no non-const (write) access!
-		return vreg(const_cast<const T*>(mC->data()),pos);
+		return vreg(const_cast<const T*>(mC.data()),pos);
 	    }
 	}
 	else {
-	    return (*mC)[pos.val()];
+	    return mC[pos.val()];
 	}
     }
 
     template <typename T, class IndexT>
     constexpr decltype(auto) OpCont<T,IndexT>::operator()() const
     {
-	return (*mC)[0];
+	return mC[0];
     }
 
     template <typename T, class IndexT>
@@ -204,13 +213,13 @@ namespace CNORXZ
     template <typename T, class IndexT>
     T* OpCont<T,IndexT>::data()
     {
-	return mC->data();
+	return mC.data();
     }
 
     template <typename T, class IndexT>
     const T* OpCont<T,IndexT>::data() const
     {
-	return mC->data();
+	return mC.data();
     }
     
     /****************
@@ -343,6 +352,12 @@ namespace CNORXZ
 	return ( std::get<Is>(mOps).rootSteps(id) << ... );
     }
 
+    template <class F, class... Ops>
+    constexpr decltype(auto) mkOperation(F&& f, const Ops&... ops)
+    {
+	return Operation<F,Ops...>(std::forward<F>(f), ops...);
+    }
+
     
     /*********************
      *   Contraction     *
diff --git a/src/include/operation/op_types.h b/src/include/operation/op_types.h
index 57967f5..b622c80 100644
--- a/src/include/operation/op_types.h
+++ b/src/include/operation/op_types.h
@@ -20,6 +20,9 @@ namespace CNORXZ
 	OpT& THIS() { return static_cast<OpT&>(*this); }
 	const OpT& THIS() const { return static_cast<const OpT&>(*this); }
 
+	constexpr decltype(auto) r() { return THIS(); }
+	constexpr decltype(auto) r() const { return THIS(); }
+	
 	template <class F, class IndexT>
 	constexpr decltype(auto) c(F&& f, const Sptr<IndexT>& ind) const;
 
@@ -93,13 +96,18 @@ namespace CNORXZ
     {
     public:
 	typedef OpInterface<OpCont<T,IndexT>> OI;
-
+	typedef typename Container<T,index_const_size<IndexT>::value,
+				   index_has_const_size<IndexT>::value>::type CT;
+	
 	constexpr OpCont() = default;
 	
 	constexpr OpCont(const Sptr<IndexT>& ind);
 	constexpr OpCont& init(const Sptr<IndexT>& ind);
 	constexpr OpCont& init(const Sptr<IndexT>& ind, const Vector<T>& c);
 
+	constexpr decltype(auto) r();
+	constexpr decltype(auto) r() const;
+	
         template <class Op>
         constexpr OpCont& operator=(const Op& in);
 
@@ -121,7 +129,7 @@ namespace CNORXZ
 	
     private:
 	Sptr<IndexT> mIndex;
-	Sptr<Vector<T>> mC;
+	CT mC;
     };
     
     
@@ -193,6 +201,9 @@ namespace CNORXZ
 	
     };
 
+    template <class F, class... Ops>
+    constexpr decltype(auto) mkOperation(F&& f, const Ops&... ops);
+
     template <class F, class... Ops>
     struct op_size<Operation<F,Ops...>>
     { static constexpr SizeT value = sizeof...(Ops); };
diff --git a/src/include/ranges/index_base.h b/src/include/ranges/index_base.h
index 5746e9c..a8e02c4 100644
--- a/src/include/ranges/index_base.h
+++ b/src/include/ranges/index_base.h
@@ -74,6 +74,14 @@ namespace CNORXZ
 	PtrId mPtrId = 0;
     };
 
+    template <class I>
+    struct index_has_const_size
+    { static constexpr bool value = false; };
+
+    template <class I>
+    struct index_const_size
+    { static constexpr SizeT value = 0; };
+
     template <class I, typename MetaType>
     IndexPtr<I,MetaType>& operator++(const IndexPtr<I,MetaType>& i);
 
diff --git a/src/include/ranges/mrange.h b/src/include/ranges/mrange.h
index 20249fe..bb57bd3 100644
--- a/src/include/ranges/mrange.h
+++ b/src/include/ranges/mrange.h
@@ -110,6 +110,13 @@ namespace CNORXZ
 
     //template <class... Indices>
     //using MIndex = GMIndex<None,Indices...>;
+    template <class... Indices>
+    struct index_has_const_size<MIndex<Indices...>>
+    { static constexpr bool value = (index_has_const_size<Indices>::value and ...); };
+
+    template <class... Indices>
+    struct index_const_size<MIndex<Indices...>>
+    { static constexpr SizeT value = (index_const_size<Indices>::value * ...); };
     
     template <class... Ranges>
     class MRangeFactory : public RangeFactoryBase
diff --git a/src/tests/operation_unit_test.cc b/src/tests/operation_unit_test.cc
index e80fbcb..39d3396 100644
--- a/src/tests/operation_unit_test.cc
+++ b/src/tests/operation_unit_test.cc
@@ -43,6 +43,35 @@ namespace
 	COpRoot<double,CIndex> mOp4;
     };
 
+    class OpCont_CR_CR_Test : public ::testing::Test
+    {
+    protected:
+
+	OpCont_CR_CR_Test()
+	{
+	    mSize1 = 7;
+	    mSize2 = 11;
+	    const SizeT off = 20;
+	    mData1 = Numbers::get(off, mSize1);
+	    mData2 = Numbers::get(off+mSize1, mSize2);
+	    mData12 = Numbers::get(off+mSize1+mSize2, mSize1*mSize2);
+	    auto cra = CRangeFactory(mSize1).create();
+	    auto crb = CRangeFactory(mSize2).create();
+	}
+
+	SizeT mSize1;
+	SizeT mSize2;
+	Vector<Double> mData1;
+	Vector<Double> mData2;
+	Vector<Double> mData12;
+	Sptr<CIndex> mCI1;
+	Sptr<CIndex> mCI2;
+	OpCont<double,CIndex> mOp1;
+	COpRoot<double,CIndex> mOp2;
+	OpCont<double,CIndex> mOp3;
+	COpRoot<double,CIndex> mOp4;
+    };
+
     TEST_F(OpCont_CR_Test, Basics)
     {
 	EXPECT_EQ(mOp2.data(), mData1.data());