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    std::imag(std::complex)

    From cppreference.com
     
    C++
     
    Numerics library
     
    std::complex
     
    Defined in header <complex>
    (1) 
    template< class T > 
T imag( const std::complex<T>& z );
    		(until C++14) 
    template< class T > 
constexpr T imag( const std::complex<T>& z );
    		(since C++14)
    Additional overloads (since C++11)
    Defined in header <complex>
    (A) 
    float       imag( float f );
double      imag( double f );
long double imag( long double f );
    		(until C++14) 
    constexpr float       imag( float f );
constexpr double      imag( double f );
constexpr long double imag( long double f );
    		(since C++14)
    (until C++23) 
    template< class FloatingPoint >
FloatingPoint imag( FloatingPoint f );
    		(since C++23)
    (B) 
    template< class Integer > 
double imag( Integer i );
    		(until C++14) 
    template< class Integer > 
constexpr double imag( Integer i );
    		(since C++14)
    1) Returns the imaginary part of the complex number z, i.e. z.imag().
    A,B) Additional overloads are provided for all integer and floating-point types, which are treated as complex numbers with zero imaginary part.
    		 (since C++11)

    Parameters

    z - complex value
    f - floating-point value
    i - integer value

    Return value

    1) The imaginary part of z.
    A) decltype(f){} (zero).
    B) 0.0.

    Notes

    The additional overloads are not required to be provided exactly as (A,B). They only need to be sufficient to ensure that for their argument num:

    • If num has a standard(until C++23) floating-point type T, then std::imag(num) has the same effect as std::imag(std::complex<T>(num)).
    • Otherwise, if num has an integer type, then std::imag(num) has the same effect as std::imag(std::complex<double>(num)).

    See also