std::complex<T>::operator+(unary), operator-(unary)

	(1)
template< class T > std::complex<T> operator+( const std::complex<T>& val );		(until C++20)
template< class T > constexpr std::complex<T> operator+( const std::complex<T>& val );		(since C++20)
	(2)
template< class T > std::complex<T> operator-( const std::complex<T>& val );		(until C++20)
template< class T > constexpr std::complex<T> operator-( const std::complex<T>& val );		(since C++20)

Implements the analogs of the unary arithmetic operators for complex numbers.

1) Returns the value of its argument

2) Negates the argument

val

the complex number argument

1) a copy of the argument, std::complex<T>(val)

2) negated argument, std::complex<T>(-val.real(), -val.imag())