# carg(3)

#### 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);

```

#### 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)

```

#### RETURNVALUE

```   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

```

#### CONFORMINGTO

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

```

#### SEEALSO

```   cabs(3), complex(7)

```

#### COLOPHON

```   This  page  is  part of release 4.09 of the Linux man-pages project.  A
description of the project, information about reporting bugs,  and  the
latest     version     of     this    page,    can    be    found    at
https://www.kernel.org/doc/man-pages/.

2015-04-19                           CARG(3)
```

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