/**
* Evaluate the derivative polynomial at the point x.
*/
template<typename _Up>
auto
derivative(_Up __x) const
-> delctype(value_type{} * _Up{});
/**
* Evaluate the integral polynomial with given integration constant at the point x.
*/
template<typename _Up>
auto
integral(value_type __c, _Up __x) const
-> delctype(value_type{} * _Up{});