acosh(3)

NAME

   acosh, acoshf, acoshl - inverse hyperbolic cosine function

SYNOPSIS

   #include <math.h>

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

   Link with -lm.

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

CONFORMING TO

   C99, POSIX.1-2001, POSIX.1-2008.

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

SEE ALSO

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

COLOPHON

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   description  of  the project, information about reporting bugs, and the
   latest    version    of    this    page,    can     be     found     at
   https://www.kernel.org/doc/man-pages/.

                              2016-03-15                          ACOSH(3)

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