Complex number for C++

complex_numbers.hpp

#include <stdexcept>
#include <cmath>
namespace complex_numbers
{
    class Complex
    {
    private:
        double _real;
        double _imag;
    public:
        Complex(double real, double imag) : _real(real), _imag(imag){};
        double real() const { return this->_real; }
        double imag() const { return this->_imag; }
        double abs() const { return std::sqrt(std::pow(this->_real, 2) + std::pow(this->_imag, 2)); }
        Complex conj() const { return Complex(this->_real, -1 * this->_imag); }
        Complex exp() const
        {
            double k = std::exp(this->_real);
            return Complex(k * std::cos(this->_imag), k * std::sin(this->_imag));
        }
        Complex operator+(const Complex &other) const { return Complex(_real + other.real(), _imag + other.imag()); }
        Complex operator-(const Complex &other) const { return Complex(_real - other.real(), _imag - other.imag()); }
        Complex operator*(const Complex &other) const
        {
            double a{_real}, b{_imag}, c{other.real()}, d{other.imag()};
            return Complex(a * c - b * d, b * c + a * d);
        }
        Complex operator/(const Complex &other) const
        {
            // only for non-zero complex number
            if (other.abs() == 0)
                throw std::domain_error("only for non-zero complex number");
            double a{_real}, b{_imag}, c{other.real()}, d{other.imag()};
            return Complex((a * c + b * d) / (c * c + d * d), (b * c - a * d) / (c * c + d * d));
        }
    };
} // namespace complex_numbers