'\" t
.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
.\"
.\" SPDX-License-Identifier: GPL-1.0-or-later
.\"
.TH carg 3 (date) "Linux man-pages (unreleased)"
.SH NAME
carg, cargf, cargl \- calculate the complex argument
.SH LIBRARY
Math library
.RI ( libm ", " \-lm )
.SH SYNOPSIS
.nf
.B #include <complex.h>
.P
.BI "double carg(double complex " z ");"
.BI "float cargf(float complex " z ");"
.BI "long double cargl(long double complex " z ");"
.fi
.SH DESCRIPTION
These functions calculate the complex argument (also called phase angle) of
.IR z ,
with a branch cut along the negative real axis.
.P
A complex number can be described by two real coordinates.
One may use rectangular coordinates and gets
.P
.in +4n
.EX
z = x + I * y
.EE
.in
.P
where
.I x\~=\~creal(z)
and
.IR y\~=\~cimag(z) .
.P
Or one may use polar coordinates and gets
.P
.in +4n
.EX
z = r * cexp(I * a)
.EE
.in
.P
where
.I r\~=\~cabs(z)
is the "radius", the "modulus", the absolute value of
.IR z ,
and
.I a\~=\~carg(z)
is the "phase angle", the argument of
.IR z .
.P
One has:
.P
.in +4n
.EX
tan(carg(z)) = cimag(z) / creal(z)
.EE
.in
.SH RETURN VALUE
The return value is in the range of [\-pi,pi].
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbx lb lb
l l l.
Interface Attribute Value
T{
.na
.nh
.BR carg (),
.BR cargf (),
.BR cargl ()
T} Thread safety MT-Safe
.TE
.SH STANDARDS
C11, POSIX.1-2008.
.SH HISTORY
glibc 2.1.
C99, POSIX.1-2001.
.SH SEE ALSO
.BR cabs (3),
.BR complex (7)
