.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
.\"
.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
.\" Distributed under GPL
.\" %%%LICENSE_END
.\"
.TH CARG 3 2008-08-11 "" "Linux Programmer's Manual"
.SH NAME
carg, cargf, cargl \- calculate the complex argument
.SH SYNOPSIS
.B #include <complex.h>
.sp
.BI "double carg(double complex " z ");"
.br
.BI "float cargf(float complex " z ");"
.br
.BI "long double cargl(long double complex " z ");"
.sp
Link with \fI\-lm\fP.
.SH DESCRIPTION
A complex number can be described by two real coordinates.
One may use rectangular coordinates and gets

.nf
    z = x + I * y
.fi

where
.IR "x\ =\ creal(z)"
and
.IR "y\ =\ cimag(z)" .
.LP
Or one may use polar coordinates and gets
.nf

    z = r * cexp(I * a)

.fi
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 .
.LP
One has:
.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 CONFORMING TO
C99.
.SH SEE ALSO
.BR cabs (3),
.BR complex (7)
.SH COLOPHON
This page is part of release 3.74 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
\%http://www.kernel.org/doc/man\-pages/.