SYNOPSIS

#include <complex.h>

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

Link with -lm.

DESCRIPTION

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)

RETURN VALUE

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

VERSIONS

These functions first appeared in glibc in version 2.1.

ATTRIBUTES

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

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

CONFORMING TO

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

COLOPHON

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