diff --git a/src/include/multi_array_base.h b/src/include/multi_array_base.h
index 15a8e2f..37a8a57 100644
--- a/src/include/multi_array_base.h
+++ b/src/include/multi_array_base.h
@@ -208,6 +208,7 @@ namespace MultiArrayTools
 	return ConstOperationRoot<T,SRanges...>(*this, inds...);
     }
 
+    template <typename T, class... SRanges>
     template <class... MappedRanges>
     ConstOperationRoot<T,SRanges...>
     MultiArrayBase<T,SRanges...>::operator()(const std::shared_ptr<typename MappedRanges::IndexType>&... inds) const
@@ -278,9 +279,10 @@ namespace MultiArrayTools
 	return ConstOperationRoot<T,SRanges...>(*this, inds...);
     }
 
+    template <typename T, class... SRanges>
     template <class... MappedRanges>
     ConstOperationRoot<T,SRanges...>
-    MultiArrayBase<T,SRanges...>::operator()(const std::shared_ptr<typename MappedRanges::IndexType>&... inds)
+    MutableMultiArrayBase<T,SRanges...>::operator()(const std::shared_ptr<typename MappedRanges::IndexType>&... inds)
     {
 	static_assert(sizeof...(SRanges) == sizeof...(MappedRanges),
 		      "number of mapped ranges must be equal to number of original ranges");
diff --git a/src/include/ranges/map_range.h b/src/include/ranges/map_range.h
index 59ee61e..ca9d473 100644
--- a/src/include/ranges/map_range.h
+++ b/src/include/ranges/map_range.h
@@ -17,6 +17,8 @@
 #include "ranges/x_to_string.h"
 #include "ranges/type_map.h"
 
+#include "xfor/xfor.h"
+
 namespace MultiArrayTools
 {
     namespace
@@ -115,7 +117,7 @@ namespace MultiArrayTools
 
 	template <class Exprs>
 	auto ifor(Exprs exs) const
-	    -> decltype(RPackNum<sizeof...(Indices)-1>::mkFors(mIPack, mOutIndex, exs));
+	    -> decltype(RPackNum<sizeof...(Indices)-1>::mkFor(mIPack, SinleExpression( mOutIndex, exs ) ));
 
 	/*
 	template <class Exprs>
@@ -236,7 +238,7 @@ namespace MultiArrayTools
     }
 
     // -> define in range_base.cc
-    std::shared_ptr<RangeFactoryBase> mkMULTI(const char** dp);
+    //std::shared_ptr<RangeFactoryBase> mkMULTI(const char** dp);
     
     /******************
      *   MapIndex   *
diff --git a/src/include/xfor/xfor.h b/src/include/xfor/xfor.h
index 6936da2..cb64be5 100644
--- a/src/include/xfor/xfor.h
+++ b/src/include/xfor/xfor.h
@@ -52,6 +52,44 @@ namespace MultiArrayHelper
 	    return BOUND;
 	}
     };
+
+    template <class IndexClass, class Expr>
+    class SingleExpression
+    {
+    private:
+	SingleExpression() = default;
+
+	const IndexClass* mIndPtr;
+	size_t mSPos;
+	size_t mMax;
+	Expr mExpr;
+
+	typedef decltype(mExpr.rootSteps()) ExtType;
+	ExtType mExt;
+
+    public:
+
+	static constexpr size_t LAYER = Expr::LAYER + 1;
+	static constexpr size_t SIZE = Expr::SIZE;
+
+	SingleExpression(const SingleExpression& in) = default;
+	SingleExpression& operator=(const SingleExpression& in) = default;
+	SingleExpression(SingleExpression&& in) = default;
+	SingleExpression& operator=(SingleExpression&& in) = default;
+	
+	SingleExpression(const std::shared_ptr<IndexClass>& indPtr,
+	    Expr expr);
+
+	SingleExpression(const IndexClass* indPtr,
+	    Expr expr);
+
+	
+	inline void operator()(size_t mlast, ExtType last) const;
+	inline void operator()(size_t mlast = 0) const;
+
+	auto rootSteps(std::intptr_t iPtrNum = 0) const -> ExtType;
+
+    };
     
     template <class IndexClass, class Expr, ForType FT = ForType::DEFAULT>
     class For
@@ -166,6 +204,61 @@ namespace MultiArrayHelper
 	return mExpr.rootSteps(iPtrNum);
     }
 
+
+
+    
+    template <class IndexClass, class Expr>
+    SingleExpression<IndexClass,Expr>::SingleExpression(const std::shared_ptr<IndexClass>& indPtr,
+				 Expr expr) :
+	mIndPtr(indPtr.get()), mSPos(mIndPtr->pos()), mMax(mIndPtr->max()), mExpr(expr),
+	mExt(expr.rootSteps( reinterpret_cast<std::intptr_t>( mIndPtr.get() )))
+    {
+	assert(mIndPtr != nullptr);
+	//VCHECK(mIndPtr->id());
+	//VCHECK(mIndPtr->max());
+    }
+
+    template <class IndexClass, class Expr>
+    SingleExpression<IndexClass,Expr>::SingleExpression(const IndexClass* indPtr,
+				 Expr expr) :
+	mIndPtr(indPtr), mSPos(mIndPtr->pos()), mMax(mIndPtr->max()),
+	mExpr(std::forward<Expr>( expr )),
+	mExt(expr.rootSteps( reinterpret_cast<std::intptr_t>( mIndPtr ) ))
+    {
+	assert(mIndPtr != nullptr);
+	//VCHECK(mIndPtr->id());
+	//VCHECK(mIndPtr->max());
+    }
+    
+    template <class IndexClass, class Expr>
+    inline void SingleExpression<IndexClass,Expr>::operator()(size_t mlast,
+							      ExtType last) const
+    {
+	//typedef typename IndexClass::RangeType RangeType;
+	const size_t pos = mIndPtr->pos();
+	const size_t mnpos = PosForward<ForType::DEFAULT>::value(mlast, mMax, pos);
+	const ExtType npos = last + mExt*pos;
+	mExpr(mnpos, npos);
+    }
+
+    template <class IndexClass, class Expr>
+    inline void SingleExpression<IndexClass,Expr>::operator()(size_t mlast) const
+    {
+	//typedef typename IndexClass::RangeType RangeType;
+	const ExtType last;
+	const size_t pos = mIndPtr->pos();
+	const size_t mnpos = PosForward<ForType::DEFAULT>::value(mlast, mMax, pos);
+	const ExtType npos = last + mExt*pos;
+	mExpr(mlast, last);
+    }
+    
+    template <class IndexClass, class Expr>
+    auto SingleExpression<IndexClass,Expr>::rootSteps(std::intptr_t iPtrNum) const
+	-> ExtType
+    {
+	return mExpr.rootSteps(iPtrNum);
+    }
+
     
 } // namespace MultiArrayHelper