static bool same_size(
         const container_type &x1 ,
         const container_type &x2
     )
 {
     return ( ( x1.size1() == x2.size1() ) && ( x1.size2() == x2.size2() ) );
 }
 static void resize( const container_type &x , container_type &dxdt )
 {
     dxdt.resize( x.size1() , x.size2() );
 }