# CARG

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

VERSIONS

ATTRIBUTES

CONFORMING TO

SEE ALSO

COLOPHON

## NAME

carg, cargf,
cargl - calculate the complex argument

## 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).

## CONFORMING TO

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

## SEE ALSO

**cabs**(3),
**complex**(7)

## COLOPHON

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