NAME    [Toc]    [Back]

     acosh, acoshf - inverse hyperbolic cosine functions

SYNOPSIS    [Toc]    [Back]

     #include <math.h>

     double
     acosh(double x);

     float
     acoshf(float x);

DESCRIPTION    [Toc]    [Back]

     The acosh() function computes the inverse hyperbolic  cosine
of the real
     argument  x.   The  acoshf()  function is a single precision
version of
     acosh().

RETURN VALUES    [Toc]    [Back]

     If x is less than one, acosh(x) and acoshf(x) return NaN and
set the
     global variable errno to EDOM.

SEE ALSO    [Toc]    [Back]

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

HISTORY    [Toc]    [Back]

     The acosh() function appeared in 4.3BSD.

OpenBSD      3.6                            May      6,      1991