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CARG(3) Library Functions Manual CARG(3)

NAME

carg, cargf, cargl - calculate the complex argument

LIBRARY

Math library (libm, -lm)

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)

RETURN VALUE

The return value is in 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

STANDARDS

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

SEE ALSO

cabs(3), complex(7)

2022-10-09 Linux man-pages 6.01