diff --git a/bench/btl/actions/action_trisolve_matrix.hh b/bench/btl/actions/action_trisolve_matrix.hh
new file mode 100644
index 000000000..18813a016
--- /dev/null
+++ b/bench/btl/actions/action_trisolve_matrix.hh
@@ -0,0 +1,165 @@
+//=====================================================
+// File   :  action_matrix_matrix_product.hh
+// Author :  L. Plagne <laurent.plagne@edf.fr)>
+// Copyright (C) EDF R&D,  lun sep 30 14:23:19 CEST 2002
+//=====================================================
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of the GNU General Public License
+// as published by the Free Software Foundation; either version 2
+// of the License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+//
+#ifndef ACTION_TRISOLVE_MATRIX_PRODUCT
+#define ACTION_TRISOLVE_MATRIX_PRODUCT
+#include "utilities.h"
+#include "STL_interface.hh"
+#include <string>
+#include "init/init_function.hh"
+#include "init/init_vector.hh"
+#include "init/init_matrix.hh"
+
+using namespace std;
+
+template<class Interface>
+class Action_trisolve_matrix {
+
+public :
+
+  // Ctor
+
+  Action_trisolve_matrix( int size ):_size(size)
+  {
+    MESSAGE("Action_trisolve_matrix Ctor");
+
+    // STL matrix and vector initialization
+
+    init_matrix<pseudo_random>(A_stl,_size);
+    init_matrix<pseudo_random>(B_stl,_size);
+    init_matrix<null_function>(X_stl,_size);
+    init_matrix<null_function>(resu_stl,_size);
+
+    for (int j=0; j<_size; ++j)
+    {
+      for (int i=0; i<j; ++i)
+        A_stl[j][i] = 0;
+      A_stl[j][j] += 3;
+    }
+
+    // generic matrix and vector initialization
+
+    Interface::matrix_from_stl(A_ref,A_stl);
+    Interface::matrix_from_stl(B_ref,B_stl);
+    Interface::matrix_from_stl(X_ref,X_stl);
+
+    Interface::matrix_from_stl(A,A_stl);
+    Interface::matrix_from_stl(B,B_stl);
+    Interface::matrix_from_stl(X,X_stl);
+
+    _cost = 0;
+    for (int j=0; j<_size; ++j)
+    {
+      _cost += 2*j + 1;
+    }
+    _cost *= _size;
+  }
+
+  // invalidate copy ctor
+
+  Action_trisolve_matrix( const  Action_trisolve_matrix & )
+  {
+    INFOS("illegal call to Action_trisolve_matrix Copy Ctor");
+    exit(0);
+  }
+
+  // Dtor
+
+  ~Action_trisolve_matrix( void ){
+
+    MESSAGE("Action_trisolve_matrix Dtor");
+
+    // deallocation
+
+    Interface::free_matrix(A,_size);
+    Interface::free_matrix(B,_size);
+    Interface::free_matrix(X,_size);
+
+    Interface::free_matrix(A_ref,_size);
+    Interface::free_matrix(B_ref,_size);
+    Interface::free_matrix(X_ref,_size);
+
+  }
+
+  // action name
+
+  static inline std::string name( void )
+  {
+    return "trisolve_matrix_"+Interface::name();
+  }
+
+  double nb_op_base( void ){
+    return _cost;
+  }
+
+  inline void initialize( void ){
+
+    Interface::copy_matrix(A_ref,A,_size);
+    Interface::copy_matrix(B_ref,B,_size);
+    Interface::copy_matrix(X_ref,X,_size);
+
+  }
+
+  inline void calculate( void ) {
+      Interface::trisolve_lower_matrix(A,B,X,_size);
+  }
+
+  void check_result( void ){
+
+    // calculation check
+
+//     Interface::matrix_to_stl(X,resu_stl);
+// 
+//     STL_interface<typename Interface::real_type>::matrix_matrix_product(A_stl,B_stl,X_stl,_size);
+// 
+//     typename Interface::real_type error=
+//       STL_interface<typename Interface::real_type>::norm_diff(X_stl,resu_stl);
+// 
+//     if (error>1.e-6){
+//       INFOS("WRONG CALCULATION...residual=" << error);
+// //       exit(1);
+//     }
+
+  }
+
+private :
+
+  typename Interface::stl_matrix A_stl;
+  typename Interface::stl_matrix B_stl;
+  typename Interface::stl_matrix X_stl;
+  typename Interface::stl_matrix resu_stl;
+
+  typename Interface::gene_matrix A_ref;
+  typename Interface::gene_matrix B_ref;
+  typename Interface::gene_matrix X_ref;
+
+  typename Interface::gene_matrix A;
+  typename Interface::gene_matrix B;
+  typename Interface::gene_matrix X;
+
+  int _size;
+  double _cost;
+
+};
+
+
+#endif
+
+
+