243   T& derived()  {return(static_cast<T&>(*this));}  in derived()  function
250   T const& derived() const {return(static_cast<T const&>(*this));}  in derived()  function
259   Scalar const operator[](const index_t i) const {return(this->derived()[i]);}  in operator []()
269   Scalar const operator()(const index_t r,const index_t c) const {return(this->derived()(r,c));}  in operator ()()
279   Vector const vector_op(const index_t i) const {return(this->derived().vector_op(i));}  in vector_op()
289 …ail(const index_t i,const vector_length_t remaining) const {return(this->derived().vector_op_tail(…  in vector_op_tail()
299 …Vector const matrix_op(const index_t r,const index_t c) const {return(this->derived().matrix_op(r,…  in matrix_op()
310 …t r,const index_t c,const vector_length_t remaining) const {return(this->derived().matrix_op_tail(…  in matrix_op_tail()
318   vector_length_t length() const {return(this->derived().length());}  in length()
325   vector_length_t rows() const {return(this->derived().rows());}  in rows()
332   vector_length_t columns() const {return(this->derived().columns());}  in columns()