NAME
    acoth - inverse hyperbolic cotangent

SYNOPSIS
    acoth(x [,eps])

TYPES
    x		real, with abs(x) > 1
    eps		nonzero real, defaults to epsilon()

    return	real

DESCRIPTION
    Returns the acoth of x to a multiple of eps with error less in
    absolute value than .75 * eps.

    acoth(x) is the real number v for which coth(v) = x.
    It is given by
		acoth(x) = ln((x + 1)/(x - 1))/2

EXAMPLE
    ; print acoth(2, 1e-5), acoth(2, 1e-10), acoth(2, 1e-15), acoth(2, 1e-20)
    .54931 .5493061443 .549306144334055 .5493061443340548457

LIMITS
    none

LINK LIBRARY
    NUMBER *qacoth(NUMBER *x, NUMBER *eps)

SEE ALSO
    asinh, acosh, atanh, asech, acsch, epsilon

## Copyright (C) 1999  Landon Curt Noll
##
## Calc is open software; you can redistribute it and/or modify it under
## the terms of the version 2.1 of the GNU Lesser General Public License
## as published by the Free Software Foundation.
##
## Calc is distributed in the hope that it will be useful, but WITHOUT
## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
## or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU Lesser General
## Public License for more details.
##
## A copy of version 2.1 of the GNU Lesser General Public License is
## distributed with calc under the filename COPYING-LGPL.  You should have
## received a copy with calc; if not, write to Free Software Foundation, Inc.
## 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
##
## @(#) $Revision: 30.1 $
## @(#) $Id: acoth,v 30.1 2007/03/16 11:10:42 chongo Exp $
## @(#) $Source: /usr/local/src/cmd/calc/help/RCS/acoth,v $
##
## Under source code control:	1995/11/13 03:49:01
## File existed as early as:	1995
##
## chongo <was here> /\oo/\	http://www.isthe.com/chongo/
## Share and enjoy!  :-)	http://www.isthe.com/chongo/tech/comp/calc/