1993-03-21 12:45:37 +03:00
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.\" Copyright (c) 1985, 1991 Regents of the University of California.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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1993-08-01 11:32:48 +04:00
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.\" from: @(#)atanh.3 5.2 (Berkeley) 5/6/91
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1993-08-14 17:42:09 +04:00
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.\" $Id: atanh.3,v 1.3 1993/08/14 13:42:33 mycroft Exp $
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1993-03-21 12:45:37 +03:00
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.\"
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.Dd May 6, 1991
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.Dt ATANH 3
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.Os BSD 4.3
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.Sh NAME
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.Nm atanh
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.Nd inverse hyperbolic tangent function
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.Sh SYNOPSIS
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.Fd #include <math.h>
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.Ft double
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.Fn atanh "double x"
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.Sh DESCRIPTION
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The
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.Fn atanh
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function computes the inverse hyperbolic tangent
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of the real
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argument
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.Ar x .
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For a discussion of error due to roundoff, see
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.Xr math 3 .
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.Sh RETURN VALUES
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The
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.Fn atanh
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function
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returns the inverse hyperbolic tangent of
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.Ar x
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if successful.
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On the
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.Tn VAX
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and
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.Tn Tahoe ,
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if the argument has absolute value
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bigger than or equal to 1,
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.Fn atanh
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sets the global variable
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.Va errno
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to
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.Er EDOM
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and
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a reserved operand fault is generated.
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.Sh SEE ALSO
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.Xr acosh 3 ,
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.Xr asinh 3 ,
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.Xr exp 3 ,
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.Xr infnan 3
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.Xr math 3 ,
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.Sh HISTORY
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The
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.Fn atanh
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function appeared in
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.Bx 4.3 .
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