| NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | STANDARDS | HISTORY | SEE ALSO | COLOPHON | |
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acosh(3)                 Library Functions Manual                acosh(3)
       acosh, acoshf, acoshl - inverse hyperbolic cosine function
       Math library (libm, -lm)
       #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
       These functions calculate the inverse hyperbolic cosine of x; that
       is the value whose hyperbolic cosine is x.
       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.
       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.
       For an explanation of the terms used in this section, see
       attributes(7).
       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                            │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │ acosh(), acoshf(), acoshl()          │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘
       C11, POSIX.1-2008.
       C99, POSIX.1-2001.
       The variant returning double also conforms to SVr4, 4.3BSD.
       asinh(3), atanh(3), cacosh(3), cosh(3), sinh(3), tanh(3)
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Linux man-pages 6.15            2025-05-17                       acosh(3)
Pages that refer to this page: asinh(3), atanh(3), cacosh(3), cosh(3), sinh(3), tanh(3)