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std::conj(std::complex)

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< cpp‎ | numeric‎ | complex
 
C++
 
Numerics library
 
std::complex
 
Defined in header <complex>
(1)
template< class T >
std::complex<T> conj( const std::complex<T>& z );
 (until C++20)
template< class T >
constexpr std::complex<T> conj( const std::complex<T>& z );
 (since C++20)
Additional overloads (since C++11)
Defined in header <complex>
(A)
std::complex<float>       conj( float f );

std::complex<double>      conj( double f );

std::complex<long double> conj( long double f );
 (until C++20)
constexpr std::complex<float>       conj( float f );

constexpr std::complex<double>      conj( double f );

constexpr std::complex<long double> conj( long double f );
 (since C++20)
(until C++23)
template< class FloatingPoint >
constexpr std::complex<FloatingPoint> conj( FloatingPoint f );
 (since C++23)
(B)
template< class Integer >
constexpr std::complex<double> conj( Integer i );
 (until C++20)
template< class Integer >
constexpr std::complex<double> conj( Integer i );
 (since C++20)
1) Computes the complex conjugate of z by reversing the sign of the imaginary part.
A,B) Additional overloads are provided for all integer and floating-point types, which are treated as complex numbers with zero imaginary component.
 (since C++11)

Contents

[edit] Parameters

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

[edit] Return value

1) The complex conjugate of z.
A) std::complex(f).
B) std::complex<double>(i).

[edit] 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::conj(num) has the same effect as std::conj(std::complex<T>(num)).
  • Otherwise, if num has an integer type, then std::conj(num) has the same effect as std::conj(std::complex<double>(num)).

[edit] Example

Run this code
#include <complex>
#include <iostream>
 
int main()
{
    std::complex<double> z(1.0, 2.0);
    std::cout << "The conjugate of " << z << " is " << std::conj(z) << '\n'
              << "Their product is " << z * std::conj(z) << '\n';
}

Output: 

The conjugate of (1,2) is (1,-2)
Their product is (5,0)

[edit] See also

 returns the magnitude of a complex number
(function template) [edit]
returns the squared magnitude
(function template) [edit]
constructs a complex number from magnitude and phase angle
(function template) [edit]
C documentation for conj
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