.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)

.\"

.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)

.\" Distributed under GPL

.\" %%%LICENSE_END

.\"

.TH CARG 3 2017-09-15 "" "Linux Programmer's Manual"

.SH NAME

carg, cargf, cargl \- calculate the complex argument

.SH SYNOPSIS

.B #include <complex.h>

.PP

.BI "double carg(double complex " z ");"

.br

.BI "float cargf(float complex " z ");"

.br

.BI "long double cargl(long double complex " z ");"

.PP

Link with \fI\-lm\fP.

.SH DESCRIPTION

These functions calculate the complex argument (also called phase angle) of

.IR z ,

with a branch cut along the negative real axis.

.PP

A complex number can be described by two real coordinates.

One may use rectangular coordinates and gets

.PP

.nf

    z = x + I * y

.fi

.PP

where

.IR "x\ =\ creal(z)"

and

.IR "y\ =\ cimag(z)" .

.PP

Or one may use polar coordinates and gets

.PP

.nf

    z = r * cexp(I * a)

.fi

.PP

where

.IR "r\ =\ cabs(z)"

is the "radius", the "modulus", the absolute value of

.IR z ,

and

.IR "a\ =\ carg(z)"

is the "phase angle", the argument of

.IR z .

.PP

One has:

.PP

.nf

    tan(carg(z)) = cimag(z) / creal(z)

.fi

.SH RETURN VALUE

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

.SH VERSIONS

These functions first appeared in glibc in version 2.1.

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.TS

allbox;

lbw24 lb lb

l l l.

Interface	Attribute	Value

T{

.BR carg (),

.BR cargf (),

.BR cargl ()

T}	Thread safety	MT-Safe

.TE

.SH CONFORMING TO

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

.SH SEE ALSO

.BR cabs (3),

.BR complex (7)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I 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/.