template<class T> constexpr complex(const T& re = T(), const T& im = T());
Effects:
Constructs an object of class
complex.
Postconditions:
real() == re && imag() == im.
constexpr T real() const;
Returns: The value of the real component.
void real(T val);
Effects: Assigns val to the real component.
constexpr T imag() const;
Returns: The value of the imaginary component.
void imag(T val);
Effects: Assigns val to the imaginary component.