.\" Copyright 2002 Walter Harms (walter.harms@informatik.uni-oldenburg.de)
.\" Distributed under GPL
.\"
.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 \fIx\ =\ creal(z)\fP and \fIy\ =\ cimag(z)\fP.
.LP
Or one may use polar coordinates and gets
.nf

    z = r * cexp(I * a)

.fi
where \fIr\ =\ cabs(z)\fP
is the "radius", the "modulus", the absolute value of \fIz\fP, and
\fIa\ =\ carg(z)\fP
is the "phase angle", the argument of \fIz\fP.
.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)