carg(3) - Linux man page

Name

carg, cargf, cargl - calculate the complex argument

#include <complex.h>

double carg(double complex z);
float cargf(float complex z);
long double cargl(long double complex z);

Link with -lm.

A complex number can be described by two real coordinates. One may use rectangular

coordinates and gets

z = x + I * y

where x = creal(z) and y = cimag(z).

Or one may use polar coordinates and gets

z = r * cexp(I * a)

where r = cabs(z) is the "radius", the "modulus", the absolute value of z, and a = carg(z) is the "phase angle", the argument of z.

One has:

tan(carg(z)) = cimag(z) / creal(z)

The return value is the range of [-pi,pi].

These functions first appeared in glibc in version 2.1.

C99.

atan(3), atan2(3), complex(5)