ACOSH(3)            Linux Programmer's Manual            ACOSH(3)

NAME
       acosh - inverse hyperbolic cosine function

SYNOPSIS
       #include <math.h>

       double acosh(double x);

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
       SVID 3, POSIX, BSD 4.3, ISO 9899

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

                          June 13, 1993                         1