# carg - Man Page

calculate the complex argument

## Library

Math library (libm, -lm)

## Synopsis

```#include <complex.h>

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

## 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 in the range of [-pi,pi].

## Versions

These functions were added in glibc 2.1.

## Attributes

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

InterfaceAttributeValue