NAME

       eye - the identity matrix

DESCRIPTION

       Following octave, the name eye_rep class is used in place of I to denote identity matrices
       because I is often used as a subscript or as  sqrt(-1).  The  dimensions  of  eye_rep  are
       determined  by  the  context.  This class is here usefull in the context of preconditioner
       interfaces: it allows calls of algorithms without any preconditioners, e.g.

           int status = pcg (a, x, b, eye_rep<Float>(), 100, 1e-7);

IMPLEMENTATION

       template<class T, class M = rheo_default_memory_model>
       class eye_rep : public solver_abstract_rep<T,M> {
       public:
         eye_rep (const solver_option_type& opt = solver_option_type());
         void update_values (const csr<T,M>&) {}
         vec<T,M> operator*   (const vec<T,M>& x) const { return x; }
         vec<T,M> solve       (const vec<T,M>& x) const { return x; }
         vec<T,M> trans_solve (const vec<T,M>& x) const { return x; }
       };