redhat man page for acosh

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)

								    1993-06-13								  ACOSH(3)