NAME

       eye - the identity matrix

DESCRIPTION

       Following  matlab,  the  name  eye() 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()  are  determined  by  context.   The
       preconditioner interface is usefull when calling algorithms without any preconditioners, e.g.

           int status = pcg (a, x, b, eye(), 100, 1e-7);

IMPLEMENTATION

       class eye {
       public:
         eye() {}
         template<class T> const vec<T>& operator* (const vec<T>& x) const { return x; }
         template<class T> const vec<T>& solve (const vec<T>& x) const { return x; }
         template<class T> const vec<T>& trans_solve (const vec<T>& x) const { x; }
       };

rheolef-6.5                                        rheolef-6.5                                     eye(2rheolef)