ACOSH(3)                 BSD Library Functions Manual                 ACOSH(3)

NAME
     acosh -- inverse hyperbolic cosine function

SYNOPSIS
     ##include <>

     double
     acosh(double x);

     long double
     acoshl(long double x);

     float
     acoshf(float x);

DESCRIPTION
     The acosh() function computes the principle value of the inverse hyper-
     bolic cosine of x.  The result is in the range [0, ]infinity].

SPECIAL VALUES
     acosh(1) returns ]0.

     acosh(x) returns a NAN and raises the "invalid" floating-point exception
     for x < 1.

     acosh(]infinity) returns ]infinity.

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

STANDARDS
     The acosh() function conforms to ISO/IEC 9899:1999(E).

HISTORY
     The acosh() and acoshf() function appeared in 4.3BSD.

4.3 Berkeley Distribution      November 15, 2002     4.3 Berkeley Distribution