diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9499092..5ee9b3f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -123,6 +123,14 @@ else()
   endif()
 endif()
 
+# CHECK LIBRARIES : mpi
+
+if(DEFINED ENABLE_mpi)
+  set(ENABLE_mpi ${ENABLE_mpi} CACHE BOOL "enable mpi")
+else()
+  set(ENABLE_mpi TRUE CACHE BOOL "enable mpi")
+endif()
+
 # DEFINES
 
 add_definitions(-DVERSION="${VERSION}")
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 1d60ecb..4d753fc 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -12,4 +12,8 @@ if(ENABLE_cereal)
   add_subdirectory(opt/cereal)
 endif()
 
+if(ENABLE_mpi)
+  add_subdirectory(opt/mpi)
+endif()
+
 install(DIRECTORY include/ DESTINATION ${INSTALL_PATH}/include/cnorxz)
diff --git a/src/include/ranges/yrange.h b/src/include/ranges/yrange.h
index 06cb273..e85a2cf 100644
--- a/src/include/ranges/yrange.h
+++ b/src/include/ranges/yrange.h
@@ -311,6 +311,7 @@ namespace CNORXZ
     public:
 	typedef RangeBase RB;
 	typedef YIndex IndexType;
+	typedef typename IndexType::MetaType MetaType;
 
 	friend YRangeFactory;
 
diff --git a/src/opt/mpi/CMakeLists.txt b/src/opt/mpi/CMakeLists.txt
new file mode 100644
index 0000000..6416c7c
--- /dev/null
+++ b/src/opt/mpi/CMakeLists.txt
@@ -0,0 +1,16 @@
+
+find_package(MPI REQUIRED)
+if(MPI_FOUND)
+  include_directories(${MPI_C_INCLUDE_DIRS})
+else()
+  message(FATAL_ERROR "HDF5 not found")
+endif()
+message(STATUS "mpi lib = ${MPI_C_LIBRARIES}")
+set(MPI_LIBS ${MPI_LIBRARIES})
+
+include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
+
+add_subdirectory(lib)
+add_subdirectory(tests)
+
+install(DIRECTORY include/ DESTINATION ${INSTALL_PATH}/include/cnorxz/mpi)
diff --git a/src/opt/mpi/include/cnorxz_mpi.cc.h b/src/opt/mpi/include/cnorxz_mpi.cc.h
new file mode 100644
index 0000000..7a2846c
--- /dev/null
+++ b/src/opt/mpi/include/cnorxz_mpi.cc.h
@@ -0,0 +1,14 @@
+// -*- C++ -*-
+/**
+
+   @file opt/mpi/include/cnorxz_mpi.cc.h
+   @brief CNORXZ MPI template sources header
+
+   Copyright (c) 2024 Christian Zimmermann. All rights reserved.
+   Mail: chizeta@f3l.de
+
+ **/
+
+#include "mpi_wrappers.cc.h"
+//#include "rop_types.cc.h"
+#include "rrange.cc.h"
diff --git a/src/opt/mpi/include/cnorxz_mpi.h b/src/opt/mpi/include/cnorxz_mpi.h
new file mode 100644
index 0000000..dac771d
--- /dev/null
+++ b/src/opt/mpi/include/cnorxz_mpi.h
@@ -0,0 +1,20 @@
+// -*- C++ -*-
+/**
+
+   @file opt/mpi/include/cnorxz_mpi.h
+   @brief CNORXZ MPI main header
+
+   Copyright (c) 2024 Christian Zimmermann. All rights reserved.
+   Mail: chizeta@f3l.de
+
+ **/
+
+#include "mpi_base.h"
+#include "mpi_wrappers.h"
+//#include "raindex.h"
+//#include "rarray.h"
+//#include "rop_types.h"
+#include "rrange.h"
+#include "typemap.h"
+
+#include "cnorxz_mpi.cc.h"
diff --git a/src/opt/mpi/include/mpi_base.h b/src/opt/mpi/include/mpi_base.h
index 678eddb..bcb8cf0 100644
--- a/src/opt/mpi/include/mpi_base.h
+++ b/src/opt/mpi/include/mpi_base.h
@@ -20,6 +20,14 @@ namespace CNORXZ
 {
     namespace mpi
     {
+	// class declarations
+
+	template <class RangeI, class RangeK>
+	class RRange;
+
+	template <class IndexI, class IndexK>
+	class RIndex;
+	
 	// wrapper functions
 	
 	/** Get number of THIS rank. */
diff --git a/src/opt/mpi/include/mpi_wrappers.cc.h b/src/opt/mpi/include/mpi_wrappers.cc.h
index 5979385..dce47ce 100644
--- a/src/opt/mpi/include/mpi_wrappers.cc.h
+++ b/src/opt/mpi/include/mpi_wrappers.cc.h
@@ -22,9 +22,9 @@ namespace CNORXZ
 	template <typename T>
 	void BCast<T>::bcast(T& d, SizeT root)
 	{
-	    static_assert( TypeMap<T>::exists, "no bcast implementation for given type" );
+	    static_assert( Typemap<T>::exists, "no bcast implementation for given type" );
 	    const int ret = MPI_Bcast( reinterpret_cast<void*>(&d), 1,
-				       TypeMap<T>::value, MPI_COMM_WORLD );
+				       Typemap<T>::value(), root, MPI_COMM_WORLD );
 	    CXZ_ASSERT(ret == MPI_SUCCESS, "got bcast error = " << ret);
 	    return;
 	}
@@ -35,7 +35,7 @@ namespace CNORXZ
 	{
 	    SizeT size = d.size();
 	    const int ret = MPI_Bcast( reinterpret_cast<void*>(&size), 1,
-				       MPI_UNSIGNED_LONG, MPI_COMM_WORLD );
+				       MPI_UNSIGNED_LONG, root, MPI_COMM_WORLD );
 	    CXZ_ASSERT(ret == MPI_SUCCESS, "got bcast error = " << ret);
 	    if(size != d.size()){
 		d.resize(size);
@@ -47,7 +47,7 @@ namespace CNORXZ
 	    }
 	    else {
 		const int ret2 = MPI_Bcast( reinterpret_cast<void*>(d.data()), size,
-					    TypeMap<T>::value, MPI_COMM_WORLD );
+					    Typemap<T>::value(), root, MPI_COMM_WORLD );
 		CXZ_ASSERT(ret2 == MPI_SUCCESS, "got bcast error = " << ret2);
 	    }
 	}
@@ -55,15 +55,15 @@ namespace CNORXZ
 	template <typename T, SizeT N>
 	void BCast<Arr<T,N>>::bcast(Arr<T,N>& d, SizeT root)
 	{
-	    if constexpr( BCast<T,N>::special ){
+	    if constexpr( BCast<T>::special ){
 		for(auto& x: d){
 		    bcast(x, root);
 		}
 	    }
 	    else {
 		const int ret = MPI_Bcast( reinterpret_cast<void*>(d.data()), N,
-					   TypeMap<T>::value, MPI_COMM_WORLD );
-		CXZ_ASSERT(ret == MPI_SUCCESS, "got bcast error = " << ret2);
+					   Typemap<T>::value(), root, MPI_COMM_WORLD );
+		CXZ_ASSERT(ret == MPI_SUCCESS, "got bcast error = " << ret);
 	    }
 	}
 
@@ -71,25 +71,25 @@ namespace CNORXZ
 	{
 	    SizeT size = d.size();
 	    const int ret = MPI_Bcast( reinterpret_cast<void*>(&size), 1,
-				       MPI_UNSIGNED_LONG, MPI_COMM_WORLD );
+				       MPI_UNSIGNED_LONG, root, MPI_COMM_WORLD );
 	    CXZ_ASSERT(ret == MPI_SUCCESS, "got bcast error = " << ret);
 	    if(size != d.size()){
 		d.resize(size);
 	    }
-	    const int ret = MPI_Bcast( reinterpret_cast<void*>(d.data()), size,
-				       MPI_CHAR, MPI_COMM_WORLD );
-	    CXZ_ASSERT(ret == MPI_SUCCESS, "got bcast error = " << ret);
+	    const int ret2 = MPI_Bcast( reinterpret_cast<void*>(d.data()), size,
+				       MPI_CHAR, root, MPI_COMM_WORLD );
+	    CXZ_ASSERT(ret2 == MPI_SUCCESS, "got bcast error = " << ret2);
 	}
 
 	template <typename... Ts>
 	void BCast<Tuple<Ts...>>::bcast(Tuple<Ts...>& d, SizeT root)
 	{
 	    if constexpr( ( BCast<Ts>::special or ... ) ){
-		ifor<0,sizeof...(Ts)>( [&](auto i) { bcast( std::get<i>(d), root ); }, NoF {} );
+		iter<0,sizeof...(Ts)>( [&](auto i) { bcast( std::get<i>(d), root ); }, NoF {} );
 	    }
 	    else {
 		const int ret = MPI_Bcast( reinterpret_cast<void*>(&d), sizeof(d),
-					   MPI_BYTE, MPI_COMM_WORLD );
+					   MPI_BYTE, root, MPI_COMM_WORLD );
 		CXZ_ASSERT(ret == MPI_SUCCESS, "got bcast error = " << ret);
 	    }
 	}
@@ -97,7 +97,8 @@ namespace CNORXZ
 	template <typename T>
 	void bcast(T& d, SizeT root)
 	{
-	    return BCast<T>(d, root);
+	    BCast<T>::bcast(d, root);
+	    return;
 	}
 	
     } // namespace mpi
diff --git a/src/opt/mpi/include/mpi_wrappers.h b/src/opt/mpi/include/mpi_wrappers.h
index caee97b..2bd00a1 100644
--- a/src/opt/mpi/include/mpi_wrappers.h
+++ b/src/opt/mpi/include/mpi_wrappers.h
@@ -12,8 +12,7 @@
 #ifndef __cxz_mpi_wrappers_h__
 #define __cxz_mpi_wrappers_h__
 
-#include "mpi.h"
-#include "cnorxz.h"
+#include "mpi_base.h"
 #include "typemap.h"
 
 namespace CNORXZ
diff --git a/src/opt/mpi/include/rrange.cc.h b/src/opt/mpi/include/rrange.cc.h
index d928457..d8c4063 100644
--- a/src/opt/mpi/include/rrange.cc.h
+++ b/src/opt/mpi/include/rrange.cc.h
@@ -14,6 +14,7 @@
 
 #include "rrange.h"
 #include "mpi_wrappers.h"
+#include "mpi_wrappers.cc.h"
 
 namespace CNORXZ
 {
@@ -27,24 +28,24 @@ namespace CNORXZ
 	template <class IndexI, class IndexK>
 	RIndex<IndexI,IndexK>::RIndex(const RIndex& in) :
 	    mRange(in.mRange),
-	    mI(std::make_shared<Index>(mRange->local())),
-	    mK(std::make_shared<YIndex>(mRange->geom()))
+	    mI(std::make_shared<IndexI>(mRange->local())),
+	    mK(std::make_shared<IndexK>(mRange->geom()))
 	{
 	    *this = in.lex();
 	}
 
 	template <class IndexI, class IndexK>
-	RIndex& RIndex<IndexI,IndexK>::operator=(const RIndex& in)
+	RIndex<IndexI,IndexK>& RIndex<IndexI,IndexK>::operator=(const RIndex& in)
 	{
 	    mRange = in.mRange;
-	    mI = std::make_shared<Index>(mRange->local());
-	    mK = std::make_shared<YIndex>(mRange->geom());
+	    mI = std::make_shared<IndexI>(mRange->local());
+	    mK = std::make_shared<IndexK>(mRange->geom());
 	    *this = in.lex();
 	    return *this;
 	}
 
 	template <class IndexI, class IndexK>
-	RIndex<IndexI,IndexK>::RIndex(const RangePtr& global, SizeT lexpos = 0) :
+	RIndex<IndexI,IndexK>::RIndex(const RangePtr& global, SizeT lexpos) :
 	    mRange(rangeCast<RangeType>(global)),
 	    mI(std::make_shared<IndexI>(mRange->local())),
 	    mK(std::make_shared<IndexK>(mRange->geom()))
@@ -56,7 +57,7 @@ namespace CNORXZ
 	RIndex<IndexI,IndexK>& RIndex<IndexI,IndexK>::operator=(SizeT pos)
 	{
 	    IB::mPos = pos; // = lex
-	    if(lexpos >= lmax().val()){
+	    if(pos >= lmax().val()){
 		IB::mPos = pmax().val();
 		return *this;
 	    }
@@ -155,15 +156,15 @@ namespace CNORXZ
 	}
 
 	template <class IndexI, class IndexK>
-	constexpr RIndex<IndexI,IndexK>::decltype(auto) pmax() const
+	constexpr decltype(auto) RIndex<IndexI,IndexK>::pmax() const
 	{
-	    return mK->lmax().val() * mI->lmax().val();
+	    return UPos(mK->lmax().val() * mI->lmax().val());
 	}
 
 	template <class IndexI, class IndexK>
-	constexpr RIndex<IndexI,IndexK>::decltype(auto) lmax() const
+	constexpr decltype(auto) RIndex<IndexI,IndexK>::lmax() const
 	{
-	    return mK->lmax().val() * mI->lmax().val();
+	    return UPos(mK->lmax().val() * mI->lmax().val());
 	}
 
 	template <class IndexI, class IndexK>
@@ -173,7 +174,7 @@ namespace CNORXZ
 	}
 
 	template <class IndexI, class IndexK>
-	MetaType RIndex<IndexI,IndexK>::operator*() const
+	typename RIndex<IndexI,IndexK>::MetaType RIndex<IndexI,IndexK>::operator*() const
 	{
 	    return meta();
 	}
@@ -185,7 +186,7 @@ namespace CNORXZ
 	}
 
 	template <class IndexI, class IndexK>
-	Sptr<RangeType> RIndex<IndexI,IndexK>::range() const
+	Sptr<typename RIndex<IndexI,IndexK>::RangeType> RIndex<IndexI,IndexK>::range() const
 	{
 	    return mRange;
 	}
@@ -194,7 +195,7 @@ namespace CNORXZ
 	template <SizeT I>
 	decltype(auto) RIndex<IndexI,IndexK>::stepSize(const IndexId<I>& id) const
 	{
-	    return mK->stepSize(id) * mI->lmax().val() + mI->stepSize(id);
+	    return mK->stepSize(id) * mI->lmax() + mI->stepSize(id);
 	}
 
 	template <class IndexI, class IndexK>
@@ -202,16 +203,20 @@ namespace CNORXZ
 	{
 	    const SizeT r = mK->lex();
 	    String o;
-	    broadcast(r, mI->stringMeta(), &o);
+	    auto x = mI->stringMeta();
+	    bcast(x, r);
 	    return o;
 	}
 
 	template <class IndexI, class IndexK>
-	MetaType RIndex<IndexI,IndexK>::meta() const
+	typename RIndex<IndexI,IndexK>::MetaType RIndex<IndexI,IndexK>::meta() const
 	{
-	    const SizeT r = mK->lex();
 	    MetaType o;
-	    broadcast(r, mI->meta(), &o);
+	    if constexpr(Typemap<MetaType>::exists){
+		auto x = mI->meta();
+		const SizeT r = mK->lex();
+		bcast(x, r);
+	    }
 	    return o;
 	}
 
@@ -253,7 +258,7 @@ namespace CNORXZ
 	constexpr decltype(auto) RIndex<IndexI,IndexK>::ifor(const Xpr& xpr, F&& f) const
 	{
 	    CXZ_ERROR("not implemented");
-	    return 0;
+	    return xpr;
 	}
 
 	template <class IndexI, class IndexK>
@@ -276,7 +281,7 @@ namespace CNORXZ
 	}
 
 	template <class IndexI, class IndexK>
-	Sptr<Index> RIndex<IndexI,IndexK>::local() const
+	Sptr<IndexI> RIndex<IndexI,IndexK>::local() const
 	{
 	    return mI;
 	}
@@ -299,8 +304,9 @@ namespace CNORXZ
 		       << ") does not match number of ranks ( = " << s <<  ")");
 	    if constexpr(has_static_sub<typename RangeI::IndexType>::value and
 			 has_static_sub<typename RangeK::IndexType>::value) {
-		static_assert(typename RangeI::NR == typename RangeK::NR,
-			      "ranges have to be of same dimension");
+		constexpr SizeT NRI = RangeI::NR;
+		constexpr SizeT NRK = RangeK::NR;
+		static_assert(NRI == NRK, "ranges have to be of same dimension");
 	    }
 	    else {
 		CXZ_ASSERT(ri->dim() == rk->dim(), "ranges have to be of same dimension, got "
@@ -311,7 +317,7 @@ namespace CNORXZ
 	template <class RangeI, class RangeK>
 	void RRangeFactory<RangeI,RangeK>::make()
 	{
-	    Vector<Uuid> key = { mRI->key(), mRK->key() };
+	    Vector<Uuid> key = { mRI->id(), mRK->id() };
 	    const auto& info = typeid(RRange<RangeI,RangeK>);
 	    mProd = this->fromCreated(info, key);
 	    if(mProd == nullptr) {
@@ -397,7 +403,7 @@ namespace CNORXZ
 	}
 	    
 	template <class RangeI, class RangeK>
-	const MetaType RRange<RangeI,RangeK>::get(SizeT pos) const
+	const typename RRange<RangeI,RangeK>::MetaType RRange<RangeI,RangeK>::get(SizeT pos) const
 	{
 	    return (this->begin()+pos)->meta();
 	}
@@ -424,6 +430,12 @@ namespace CNORXZ
 	    mLocal(loc),
 	    mGeom(geom)
 	{}
+
+	template <class RangeI, class RangeK>
+	Vector<Uuid> RRange<RangeI,RangeK>::key() const
+	{
+	    return Vector<Uuid> { mLocal->id(), mGeom->id() };
+	}
 	
     } // namespace mpi
 } // namespace CNORXZ
diff --git a/src/opt/mpi/include/rrange.h b/src/opt/mpi/include/rrange.h
index 80a9a53..522111c 100644
--- a/src/opt/mpi/include/rrange.h
+++ b/src/opt/mpi/include/rrange.h
@@ -12,7 +12,7 @@
 #ifndef __cxz_mpi_rrange_h__
 #define __cxz_mpi_rrange_h__
 
-#include "cnorxz.h"
+#include "mpi_base.h"
 
 namespace CNORXZ
 {
@@ -140,7 +140,7 @@ namespace CNORXZ
 	    SizeT rank() const;
 
 	    /** Get the local index on THIS rank. */
-	    Sptr<IndexI,IndexK> local() const;
+	    Sptr<IndexI> local() const;
 	    //!!!
 	
 	private:
@@ -237,6 +237,7 @@ namespace CNORXZ
 	    Sptr<RangeI> mLocal; /**< Local range of THIS rank. */
 	    Sptr<RangeK> mGeom; /**< Rank geometry range. */
 	
+	    virtual Vector<Uuid> key() const override final;
 	};
 
 	/** Create RRange from global range and given rank geometry.
diff --git a/src/opt/mpi/include/typemap.h b/src/opt/mpi/include/typemap.h
index b0e20c9..f5c66ee 100644
--- a/src/opt/mpi/include/typemap.h
+++ b/src/opt/mpi/include/typemap.h
@@ -18,42 +18,42 @@ namespace CNORXZ
 	struct Typemap<int>
 	{
 	    static constexpr bool exists = true;
-	    static constexpr MPI_Datatype value = MPI_INT;
+	    static MPI_Datatype value() { return MPI_INT; }
 	};
 
 	template <>
 	struct Typemap<unsigned>
 	{
 	    static constexpr bool exists = true;
-	    static constexpr MPI_Datatype value = MPI_UNSIGNED;
+	    static MPI_Datatype value() { return MPI_UNSIGNED; }
 	};
 
 	template <>
 	struct Typemap<long int>
 	{
 	    static constexpr bool exists = true;
-	    static constexpr MPI_Datatype value = MPI_LONG;
+	    static MPI_Datatype value() { return MPI_LONG; }
 	};
 
 	template <>
 	struct Typemap<unsigned long>
 	{
 	    static constexpr bool exists = true;
-	    static constexpr MPI_Datatype value = MPI_UNSIGNED_LONG;
+	    static MPI_Datatype value() { return MPI_UNSIGNED_LONG; }
 	};
 
 	template <>
 	struct Typemap<double>
 	{
 	    static constexpr bool exists = true;
-	    static constexpr MPI_Datatype value = MPI_DOUBLE;
+	    static MPI_Datatype value() { return MPI_DOUBLE; }
 	};
 
 	template <>
 	struct Typemap<float>
 	{
 	    static constexpr bool exists = true;
-	    static constexpr MPI_Datatype value = MPI_FLOAT;
+	    static MPI_Datatype value() { return MPI_FLOAT; }
 	};
 
 	// further !!!
diff --git a/src/opt/mpi/lib/CMakeLists.txt b/src/opt/mpi/lib/CMakeLists.txt
new file mode 100644
index 0000000..8d2e833
--- /dev/null
+++ b/src/opt/mpi/lib/CMakeLists.txt
@@ -0,0 +1,18 @@
+
+set(libcnorxzmpi_a_SOURCES
+  ${CMAKE_CURRENT_SOURCE_DIR}/mpi_base.cc
+  ${CMAKE_CURRENT_SOURCE_DIR}/rrange.cc
+  )
+
+add_library(cnorxzmpi_obj OBJECT
+  ${libcnorxzmpi_a_SOURCES}
+  )
+
+set_target_properties(cnorxzmpi_obj PROPERTIES POSITION_INDEPENDENT_CODE TRUE)
+
+add_library(cnorxzmpi SHARED
+  $<TARGET_OBJECTS:cnorxzmpi_obj>
+  )
+set_target_properties(cnorxzmpi PROPERTIES POSITION_INDEPENDENT_CODE TRUE)
+
+install(TARGETS cnorxzmpi LIBRARY DESTINATION ${INSTALL_PATH}/lib)
diff --git a/src/opt/mpi/lib/rrange.cc b/src/opt/mpi/lib/rrange.cc
index ff93029..31f2c99 100644
--- a/src/opt/mpi/lib/rrange.cc
+++ b/src/opt/mpi/lib/rrange.cc
@@ -10,6 +10,7 @@
 **/
 
 #include "rrange.h"
+#include "rrange.cc.h"
 
 namespace CNORXZ
 {
@@ -27,14 +28,16 @@ namespace CNORXZ
 			   "global range has to be of same dimension as geometry range, got "
 			   << global->dim() << " and " << geom->dim());
 		MArray<RangePtr> o(geom);
-		YIndex k = geom->begin();
-		YIndex ke = geom->end();
-		auto mu = std::make_shared<CIndex>(geom->sub());
-		MArray<MArray<RangePtr>> rs(geom->sub()->range());
-		rs(mu) = operation( [&](const SizeT i) { return rsplit(globla->sub(i), geom->sub(i)); } , xpr(mu) );
-		Vector elem(geom->sub()->range());
+		YIndex k(geom);
+		YIndex ke(geom, geom->size());
+		auto mu = std::make_shared<CIndex>(geom->sub().range());
+		MArray<MArray<RangePtr>> rs(geom->sub().range());
+		rs(mu) = operation( [&](const SizeT i) { return rsplit(global->sub(i), geom->sub(i)); } , xpr(mu) );
+		Vector<RangePtr> elem(geom->dim());
 		for(; k != ke; ++k){
-		    mu->ifor( operation( [&](const SizeT i){ elem[i] = rs[i][k->pack()[i]]; }, xpr(mu) ) )();
+		    mu->ifor( operation( [&](const SizeT i, const MArray<RangePtr>& el){
+			elem[i] = el[DIndex(k.pack()[i])];
+		    }, xpr(mu), rs(mu) ), NoF {} )();
 		    o[k] = YRangeFactory(elem).create();
 		}
 		return o;
@@ -42,13 +45,13 @@ namespace CNORXZ
 	    else {
 		CXZ_ASSERT(global->size() % geom->size() == 0,
 			   "global range has to be dividible by geometry range, got "
-			   << global->size() << " and " << k->lmax().val());
+			   << global->size() << " and " << geom->size());
 		const SizeT n = global->size() / geom->size();
 		auto k = std::make_shared<CIndex>(geom);
 		auto jb = global->begin();
 		auto je = global->begin();
 		MArray<RangePtr> o(geom);
-		o(k) = operation( [&](const SizeT x){ jb = n*x; je = n*(x+1)-1; return jb.prange(je) } , xpr(k) );
+		o(k) = operation( [&](const SizeT x){ jb = n*x; je = n*(x+1)-1; return jb.prange(je); } , xpr(k) );
 		return o;
 	    }
 	}
@@ -58,14 +61,15 @@ namespace CNORXZ
 	    const MArray<RangePtr> rs = rsplit(global, geom);
 	    RangePtr o = nullptr;
 	    for(auto ri = rs.begin(); ri != rs.end(); ++ri){
-		if(ri->lex() == getRangeNum()){
+		if(ri.lex() == getRankNumber()){
 		    o = *ri;
 		}
 	    }
 	    assert(o);
 	    auto loc = rangeCast<YRange>(global);
 	    auto geo = rangeCast<YRange>(geom);
-	    return RRangeFactory<YRange,YRange>(loc, geom).create();
+	    RRangeFactory<YRange,YRange> xx(loc, geo);
+	    return RRangeFactory<YRange,YRange>(loc, geo).create();
 	}
 	
 	
diff --git a/src/opt/mpi/tests/CMakeLists.txt b/src/opt/mpi/tests/CMakeLists.txt
new file mode 100644
index 0000000..eba47b0
--- /dev/null
+++ b/src/opt/mpi/tests/CMakeLists.txt
@@ -0,0 +1,7 @@
+
+add_definitions(-DTEST_NUMBER_FILE="${CMAKE_SOURCE_DIR}/src/tests/numbers.txt")
+include_directories(${CMAKE_SOURCE_DIR}/src/tests)
+add_executable(mpirrutest rrange_unit_test.cc)
+add_dependencies(mpirrutest cnorxz cnorxzmpi test_lib)
+target_link_libraries(mpirrutest ${GTEST_BOTH_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT} ${MPI_LIBS} cnorxz cnorxzmpi test_lib)
+add_test(NAME mpirrutest COMMAND mpirrutest)
diff --git a/src/opt/mpi/tests/rrange_unit_test.cc b/src/opt/mpi/tests/rrange_unit_test.cc
new file mode 100644
index 0000000..9c470e4
--- /dev/null
+++ b/src/opt/mpi/tests/rrange_unit_test.cc
@@ -0,0 +1,69 @@
+// -*- C++ -*-
+/**
+   
+   @file opt/mpi/tests/rrange_unit_test.cc
+   @brief RRange unit tests.
+
+   Copyright (c) 2024 Christian Zimmermann. All rights reserved.
+   Mail: chizeta@f3l.de
+   
+**/
+
+#include <cstdlib>
+#include <iostream>
+
+#include "gtest/gtest.h"
+
+#include "cnorxz.h"
+#include "cnorxz_mpi.h"
+#include "test_numbers.h"
+#include "rrange.cc.h"
+
+namespace
+{
+    using namespace CNORXZ;
+    using Test::Numbers;
+    using namespace CNORXZ::mpi;
+
+    class RRange_Test : public ::testing::Test
+    {
+    protected:
+
+	RRange_Test()
+	{
+	    CXZ_ASSERT(getNumRanks() == 4, "exptected 4 ranks");
+	    Vector<Int> xs(12);
+	    Vector<Int> ts(16);
+	    mXRange = URangeFactory<Int>(xs).create();
+	    mTRange = URangeFactory<Int>(ts).create();
+	    Vector<RangePtr> rs { mTRange, mXRange, mXRange, mXRange };
+	    mGRange = YRangeFactory(rs).create();
+	    RangePtr g1 = CRangeFactory(1).create();
+	    RangePtr g2 = CRangeFactory(2).create();
+	    Vector<RangePtr> gs { g2, g1, g1, g2 };
+	    mGeom = YRangeFactory(gs).create();
+	    mRRange = rrange(mGRange, mGeom);
+	}
+
+	RangePtr mXRange;
+	RangePtr mTRange;
+	RangePtr mGRange;
+	RangePtr mGeom;
+	RangePtr mRRange;
+    };
+
+    TEST_F(RRange_Test, Basics)
+    {
+	EXPECT_EQ(mRRange->size(), mGRange->size());
+    }
+    
+}
+
+int main(int argc, char** argv)
+{
+    ::testing::InitGoogleTest(&argc, argv);
+    MPI_Init(&argc, &argv);
+    const int ret = RUN_ALL_TESTS();
+    MPI_Finalize();
+    return ret;
+}