std::arg(std::complex)

Since C++23

Header: <complex>

  1. Calculates the phase angle (in radians) of the complex number z.

# Declarations

template< class T >
T arg( const std::complex<T>& z );

Additional overloads (since C++11)

float arg( float f );
double arg( double f );
long double arg( long double f );

(until C++23)

template< class FloatingPoint >
FloatingPoint
arg( FloatingPoint f );

(since C++23)

template< class Integer >
double arg( Integer i );

# Parameters

# 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:

# Example

#include <complex>
#include <iostream>
 
int main() 
{
    std::complex<double> z1(1, 0);
    std::complex<double> z2(0, 0);
    std::complex<double> z3(0, 1);
    std::complex<double> z4(-1, 0);
    std::complex<double> z5(-1, -0.0);
    double f = 1.;
    int i = -1;
 
    std::cout << "phase angle of " << z1 << " is " << std::arg(z1) << '\n'
              << "phase angle of " << z2 << " is " << std::arg(z2) << '\n'
              << "phase angle of " << z3 << " is " << std::arg(z3) << '\n'
              << "phase angle of " << z4 << " is " << std::arg(z4) << '\n'
              << "phase angle of " << z5 << " is " << std::arg(z5) << " "
                 "(the other side of the cut)\n"
              << "phase angle of " << f << " is " << std::arg(f) << '\n'
              << "phase angle of " << i << " is " << std::arg(i) << '\n';
 
}

# See also