| Defined in header <complex> | ||
|---|---|---|
template< class T > T arg( const complex<T>& z ); | (1) | |
long double arg( long double z ); | (2) | (since C++11) |
template< class DoubleOrIngeter > double arg( DoubleOrInteger z ); | (3) | (since C++11) |
float arg( float z ); | (4) | (since C++11) |
Calculates the phase angle (in radians) of the complex number z.
(since C++11)Additional overloads are provided for float, double, long double, and all integer types, which are treated as complex numbers with zero imaginary component.
Parameters
| z | - | complex value |
Return value
If no errors occur, returns the phase angle of z in the interval (−π; π).
Errors and special cases are handled as if the function is implemented as std::atan2(std::imag(z), std::real(z)).
Example
#include <iostream>
#include <complex>
int main()
{
std::complex<double> z1(1, 0);
std::cout << "phase angle of " << z1 << " is " << std::arg(z1) << '\n';
std::complex<double> z2(0, 1);
std::cout << "phase angle of " << z2 << " is " << std::arg(z2) << '\n';
std::complex<double> z3(-1, 0);
std::cout << "phase angle of " << z3 << " is " << std::arg(z3) << '\n';
std::complex<double> z4(-1, -0.0);
std::cout << "phase angle of " << z4 << " (the other side of the cut) is "
<< std::arg(z4) << '\n';
}Output:
phase angle of (1,0) is 0 phase angle of (0,1) is 1.5708 phase angle of (-1,0) is 3.14159 phase angle of (-1,-0) (the other side of the cut) is -3.14159
See also
| returns the magnitude of a complex number (function template) | |
| constructs a complex number from magnitude and phase angle (function template) | |
| arc tangent, using signs to determine quadrants (function) | |
applies the function std::atan2 to a valarray and a value (function template) | |
C documentation for carg | |
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