carg(3) — Linux manual page

carg(3)                  Library Functions Manual                 carg(3)

NAME         top

       carg, cargf, cargl - calculate the complex argument

LIBRARY         top

       Math library (libm, -lm)

SYNOPSIS         top

       #include <complex.h>

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

DESCRIPTION         top

       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         top

       The return value is in the range of [-pi,pi].

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                            │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │ carg(), cargf(), cargl()             │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS         top

       C11, POSIX.1-2008.

HISTORY         top

       glibc 2.1.  C99, POSIX.1-2001.

SEE ALSO         top

       cabs(3), complex(7)

COLOPHON         top

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Linux man-pages 6.15            2025-05-17                        carg(3)

Pages that refer to this page: atan2(3),  atan(3),  complex(7)

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