NAME

carg, cargf, cargl - calculate the complex argument

LIBRARY

Math library (libm, -lm)

#include <complex.h>

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

These functions calculate the complex argument (also called phase angle) of z, with a branch cut along the negative real axis.

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 in the range of [-pi,pi].

These functions were added in glibc 2.1.

For an explanation of the terms used in this section, see attributes(7).

Interface	Attribute	Value
carg (), cargf (), cargl ()	Thread safety	MT-Safe

C99, POSIX.1-2001, POSIX.1-2008.