# carg(3) — Linux manual page

carg(3)                 Library Functions Manual                 carg(3)

## NAME         top

carg, cargf, cargl - calculate the complex argument

## LIBRARY         top

Math library (libm, -lm)

## SYNOPSIS         top

#include <complex.h>

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

## DESCRIPTION         top

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         top

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

## ATTRIBUTES         top

For an explanation of the terms used in this section, see
attributes(7).
┌─────────────────────────────────────┬───────────────┬─────────┐
│ Interface                           Attribute     Value   │
├─────────────────────────────────────┼───────────────┼─────────┤
│ carg(), cargf(), cargl()            │ Thread safety │ MT-Safe │
└─────────────────────────────────────┴───────────────┴─────────┘

## STANDARDS         top

C11, POSIX.1-2008.

## HISTORY         top

glibc 2.1.  C99, POSIX.1-2001.