NAME

carg, cargf, cargl — complex argument functions

SYNOPSIS

#include <complex.h>

double carg(double complex z);
float cargf(float complex z);
long double cargl(long double complex z);


DESCRIPTION

^[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2024 defers to the ISO C standard.

These functions shall compute the argument (also called phase angle) of z, with a branch cut along the negative real axis.

RETURN VALUE

These functions shall return the value of the argument in the interval [-ℼ, +ℼ].

^[MXC] If z is -0 ± i0, ±ℼ shall be returned.

If z is +0 ± i0, ±0 shall be returned.

If z is x ± i0 where x is negative, ±ℼ shall be returned.

If z is x ± i0 where x is positive, ±0 shall be returned.

If z is ±0 + iy where y is negative, -ℼ/2 shall be returned.

If z is ±0 + iy where y is positive, ℼ/2 shall be returned.

If z is -Inf ± iy where y is positive and finite, ±ℼ shall be returned.

If z is +Inf ± iy where y is positive and finite, ±0 shall be returned.

If z is x ± iInf where x is finite, ±ℼ/2 shall be returned.

If z is -Inf ± iInf, ±3ℼ/4 shall be returned.

If z is +Inf ± iInf, ±ℼ/4 shall be returned.

If the real or imaginary part of z is NaN, NaN shall be returned.

ERRORS

No errors are defined.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

cimag, conj, cproj

XBD <complex.h>

CHANGE HISTORY

First released in Issue 6. Derived from the ISO/IEC 9899:1999 standard.

Issue 8

Austin Group Defect 1302 is applied, aligning these functions with the ISO/IEC 9899:2018 standard.