ACOSH(3)                  386BSD Programmer's Manual                  ACOSH(3)

NAME
     acosh - inverse hyperbolic cosine function

SYNOPSIS
     #include <math.h>

     double
     acosh(double x)

DESCRIPTION
     The acosh() function computes the inverse hyperbolic cosine of the real
     argument x. For a discussion of error due to roundoff, see math(3).

RETURN VALUES
     The acosh() function returns the inverse hyperbolic cosine of x. On the
     VAX and Tahoe, if the argument is less than one acosh() sets the global
     variable errno to EDOM and causes a reserved operand fault.

SEE ALSO
     asinh(3),  atanh(3),  exp(3),  infnan(3) math(3),

HISTORY
     The acosh() function appeared in 4.3BSD.

4.3 Berkeley Distribution         May 6, 1991                                1