C++

Reference

<complex>

function template
<complex>

std::arg

complex (1)
template<class T> T arg (const complex<T>& x);
complex (1)
template<class T> T arg (const complex<T>& x);
arithmetic type (2)
double arg (ArithmeticType x);  // additional overloads
Phase angle of complex
Returns the phase angle (or angular component) of the complex number x, expressed in radians.

The phase angle of a complex number is the angle the theoretical vector to (real,imag) forms with the real axis (i.e., its arc tangent). It returns the same as:
1
 
atan2(x.imag(),x.real());

Only available for instantiations of complex.
Additional overloads are provided for arguments of any fundamental arithmetic type: In this case, the function assumes the value has a zero imaginary component.
The return type is double, except if the argument is float or long double (in which case, the return type is of the same type as the argument).

Parameters

x
Complex value.

Return value

Phase angle of x.
T is the type of the components of the complex type (i.e., its value type).

Example

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// arg complex example
#include <iostream>     // std::cout
#include <complex>      // std::complex, std::abs, std::arg

int main ()
{
  std::complex<double> mycomplex (3.0,4.0);

  std::cout << "The polar form of " << mycomplex;
  std::cout << " is " << std::abs(mycomplex) << "*e^i*" << std::arg(mycomplex) << "rad\n";

  return 0;
}

Output:

The polar form of (3,4) is 5*e^i*0.927295rad


See also

abs
Absolute value of complex (function template)
polar
Complex from polar components (function template)