acos(3) — Linux manual page

acos(3)                 Library Functions Manual                 acos(3)

NAME         top

       acos, acosf, acosl - arc cosine function

LIBRARY         top

       Math library (libm, -lm)

SYNOPSIS         top

       #include <math.h>

       double acos(double x);
       float acosf(float x);
       long double acosl(long double x);

   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):

       acosf(), acosl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION         top

       These functions calculate the arc cosine of x; that is the value
       whose cosine is x.

RETURN VALUE         top

       On success, these functions return the arc cosine of x in
       radians; the return value is in the range [0, pi].

       If x is a NaN, a NaN is returned.

       If x is +1, +0 is returned.

       If x is positive infinity or negative infinity, a domain error
       occurs, and a NaN is returned.

       If x is outside the range [-1, 1], a domain error occurs, and a
       NaN is returned.

ERRORS         top

       See math_error(7) for information on how to determine whether an
       error has occurred when calling these functions.

       The following errors can occur:

       Domain error: x is outside the range [-1, 1]
              errno is set to EDOM.  An invalid floating-point exception
              (FE_INVALID) is raised.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │Interface                             │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │acos(), acosf(), acosl()              │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS         top

       C11, POSIX.1-2008.

HISTORY         top

       C99, POSIX.1-2001.

       The variant returning double also conforms to C89, SVr4, 4.3BSD.

SEE ALSO         top

       asin(3), atan(3), atan2(3), cacos(3), cos(3), sin(3), tan(3)

Linux man-pages 6.04           2023-03-30                        acos(3)

Pages that refer to this page: asin(3),  atan2(3),  atan(3),  cos(3),  sin(3),  tan(3)

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