ACOSH(3)		   Linux Programmers Manual		     ACOSH(3)



NAME
       acosh, acoshf, acoshl - inverse hyperbolic cosine function

SYNOPSIS
       #include 

       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(), acoshf(), acoshl(): _BSD_SOURCE || _SVID_SOURCE ||
       _XOPEN_SOURCE >= 500 || _ISOC99_SOURCE; or cc -std=c99

DESCRIPTION
       The acosh() function calculates the inverse  hyperbolic	cosine	of  x;
       that is the value whose hyperbolic cosine is x.	If x is less than 1.0,
       acosh() returns not-a-number (NaN) and errno is set.

ERRORS
       EDOM   x is out of range.

CONFORMING TO
       SVr4, POSIX.1-2001, 4.3BSD, C89.  The float and	long  double  variants
       are C99 requirements.

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

COLOPHON
       This  page  is  part of release 3.05 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.



				  2007-07-26			      ACOSH(3)