acosh(3)                   Library Functions Manual                   acosh(3)

NAME
       acosh, acoshf, acoshl - inverse hyperbolic cosine function

LIBRARY
       Math library (libm, -lm)

SYNOPSIS
       #include <math.h>

       double acosh(double x);
       float acoshf(float x);
       long double acoshl(long double x);

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

       acosh():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || _XOPEN_SOURCE >= 500
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

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

DESCRIPTION
       These functions calculate the inverse hyperbolic cosine of x; that is
       the value whose hyperbolic cosine is x.

RETURN VALUE
       On success, these functions return the inverse hyperbolic cosine of x.

       If x is a NaN, a NaN is returned.

       If x is +1, +0 is returned.

       If x is positive infinity, positive infinity is returned.

       If x is less than 1, a domain error occurs, and the functions return a
       NaN.

ERRORS
       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 less than 1
              errno is set to EDOM.  An invalid floating-point exception
              (FE_INVALID) is raised.

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

       +--------------------------------------------+---------------+---------+
       |Interface                                   | Attribute     | Value   |
       +--------------------------------------------+---------------+---------+
       |acosh (), acoshf (), acoshl ()              | Thread safety | MT-Safe |
       +--------------------------------------------+---------------+---------+
STANDARDS
       C11, POSIX.1-2008.

HISTORY
       C99, POSIX.1-2001.

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

SEE ALSO
       asinh(3), atanh(3), cacosh(3), cosh(3), sinh(3), tanh(3)

Linux man-pages 6.7               2023-10-31                          acosh(3)