125c28e8Piotr Jasiukajtis/*
225c28e8Piotr Jasiukajtis * CDDL HEADER START
325c28e8Piotr Jasiukajtis *
425c28e8Piotr Jasiukajtis * The contents of this file are subject to the terms of the
525c28e8Piotr Jasiukajtis * Common Development and Distribution License (the "License").
625c28e8Piotr Jasiukajtis * You may not use this file except in compliance with the License.
725c28e8Piotr Jasiukajtis *
825c28e8Piotr Jasiukajtis * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
925c28e8Piotr Jasiukajtis * or http://www.opensolaris.org/os/licensing.
1025c28e8Piotr Jasiukajtis * See the License for the specific language governing permissions
1125c28e8Piotr Jasiukajtis * and limitations under the License.
1225c28e8Piotr Jasiukajtis *
1325c28e8Piotr Jasiukajtis * When distributing Covered Code, include this CDDL HEADER in each
1425c28e8Piotr Jasiukajtis * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
1525c28e8Piotr Jasiukajtis * If applicable, add the following below this CDDL HEADER, with the
1625c28e8Piotr Jasiukajtis * fields enclosed by brackets "[]" replaced with your own identifying
1725c28e8Piotr Jasiukajtis * information: Portions Copyright [yyyy] [name of copyright owner]
1825c28e8Piotr Jasiukajtis *
1925c28e8Piotr Jasiukajtis * CDDL HEADER END
2025c28e8Piotr Jasiukajtis */
2125c28e8Piotr Jasiukajtis
2225c28e8Piotr Jasiukajtis/*
2325c28e8Piotr Jasiukajtis * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
2425c28e8Piotr Jasiukajtis */
2525c28e8Piotr Jasiukajtis/*
2625c28e8Piotr Jasiukajtis * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
2725c28e8Piotr Jasiukajtis * Use is subject to license terms.
2825c28e8Piotr Jasiukajtis */
2925c28e8Piotr Jasiukajtis
30ddc0e0bRichard Lowe#pragma weak __atanhl = atanhl
3125c28e8Piotr Jasiukajtis
3225c28e8Piotr Jasiukajtis#include "libm.h"
3325c28e8Piotr Jasiukajtis
3425c28e8Piotr Jasiukajtis#define GENERIC	long double
3525c28e8Piotr Jasiukajtis#define	ATANH 	atanhl
3625c28e8Piotr Jasiukajtis
3725c28e8Piotr Jasiukajtis/* ATANH(x)
3825c28e8Piotr Jasiukajtis *                  1              2x                          x
3925c28e8Piotr Jasiukajtis *	ATANH(x) = --- * LOG(1 + -------) = 0.5 * LOG1P(2 * --------)
4025c28e8Piotr Jasiukajtis *                  2             1 - x                      1 - x
4125c28e8Piotr Jasiukajtis * Note: to guarantee ATANH(-x) = -ATANH(x), we use
42ddc0e0bRichard Lowe *                 sign(x)             |x|
4325c28e8Piotr Jasiukajtis *	ATANH(x) = ------- * LOG1P(2*-------).
4425c28e8Piotr Jasiukajtis *                    2              1 - |x|
4525c28e8Piotr Jasiukajtis *
4625c28e8Piotr Jasiukajtis * Special cases:
4725c28e8Piotr Jasiukajtis *	ATANH(x) is NaN if |x| > 1 with signal;
4825c28e8Piotr Jasiukajtis *	ATANH(NaN) is that NaN with no signal;
4925c28e8Piotr Jasiukajtis *	ATANH(+-1) is +-INF with signal.
5025c28e8Piotr Jasiukajtis *
5125c28e8Piotr Jasiukajtis */
5225c28e8Piotr Jasiukajtis
5325c28e8Piotr Jasiukajtis#define	FABS 	fabsl
5425c28e8Piotr Jasiukajtis#define	LOG1P 	log1pl
5525c28e8Piotr Jasiukajtis#define	COPYSIGN 	copysignl
5625c28e8Piotr Jasiukajtis
5725c28e8Piotr Jasiukajtis
5825c28e8Piotr Jasiukajtisextern GENERIC 	FABS(),LOG1P(),COPYSIGN();
5925c28e8Piotr Jasiukajtis
6025c28e8Piotr Jasiukajtisstatic GENERIC
6125c28e8Piotr Jasiukajtiszero	= (GENERIC) 0.0,
6225c28e8Piotr Jasiukajtishalf 	= (GENERIC) 0.5,
6325c28e8Piotr Jasiukajtisone	= (GENERIC) 1.0;
6425c28e8Piotr Jasiukajtis
6525c28e8Piotr JasiukajtisGENERIC ATANH(x)
6625c28e8Piotr JasiukajtisGENERIC x;
67ddc0e0bRichard Lowe{
6825c28e8Piotr Jasiukajtis	GENERIC t;
6925c28e8Piotr Jasiukajtis	t = FABS(x);
7025c28e8Piotr Jasiukajtis	if (t == one) return x/zero;
7125c28e8Piotr Jasiukajtis	t = t/(one-t);
7225c28e8Piotr Jasiukajtis	return COPYSIGN(half,x)*LOG1P(t+t);
7325c28e8Piotr Jasiukajtis}
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