28 Numerics library [numerics]

28.4 Complex numbers [complex.numbers]

28.4.3 Class template complex [complex]

namespace std { template<class T> class complex { public: using value_type = T; constexpr complex(const T& re = T(), const T& im = T()); constexpr complex(const complex&); template<class X> constexpr complex(const complex<X>&); constexpr T real() const; constexpr void real(T); constexpr T imag() const; constexpr void imag(T); constexpr complex& operator= (const T&); constexpr complex& operator+=(const T&); constexpr complex& operator-=(const T&); constexpr complex& operator*=(const T&); constexpr complex& operator/=(const T&); constexpr complex& operator=(const complex&); template<class X> constexpr complex& operator= (const complex<X>&); template<class X> constexpr complex& operator+=(const complex<X>&); template<class X> constexpr complex& operator-=(const complex<X>&); template<class X> constexpr complex& operator*=(const complex<X>&); template<class X> constexpr complex& operator/=(const complex<X>&); }; }
The class complex describes an object that can store the Cartesian components, real() and imag(), of a complex number.