125c28e83SPiotr Jasiukajtis /* 225c28e83SPiotr Jasiukajtis * CDDL HEADER START 325c28e83SPiotr Jasiukajtis * 425c28e83SPiotr Jasiukajtis * The contents of this file are subject to the terms of the 525c28e83SPiotr Jasiukajtis * Common Development and Distribution License (the "License"). 625c28e83SPiotr Jasiukajtis * You may not use this file except in compliance with the License. 725c28e83SPiotr Jasiukajtis * 825c28e83SPiotr Jasiukajtis * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 925c28e83SPiotr Jasiukajtis * or http://www.opensolaris.org/os/licensing. 1025c28e83SPiotr Jasiukajtis * See the License for the specific language governing permissions 1125c28e83SPiotr Jasiukajtis * and limitations under the License. 1225c28e83SPiotr Jasiukajtis * 1325c28e83SPiotr Jasiukajtis * When distributing Covered Code, include this CDDL HEADER in each 1425c28e83SPiotr Jasiukajtis * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 1525c28e83SPiotr Jasiukajtis * If applicable, add the following below this CDDL HEADER, with the 1625c28e83SPiotr Jasiukajtis * fields enclosed by brackets "[]" replaced with your own identifying 1725c28e83SPiotr Jasiukajtis * information: Portions Copyright [yyyy] [name of copyright owner] 1825c28e83SPiotr Jasiukajtis * 1925c28e83SPiotr Jasiukajtis * CDDL HEADER END 2025c28e83SPiotr Jasiukajtis */ 2125c28e83SPiotr Jasiukajtis 2225c28e83SPiotr Jasiukajtis /* 2325c28e83SPiotr Jasiukajtis * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 2425c28e83SPiotr Jasiukajtis */ 2525c28e83SPiotr Jasiukajtis /* 2625c28e83SPiotr Jasiukajtis * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 2725c28e83SPiotr Jasiukajtis * Use is subject to license terms. 2825c28e83SPiotr Jasiukajtis */ 2925c28e83SPiotr Jasiukajtis 30*ddc0e0b5SRichard Lowe #pragma weak __atanh = atanh 3125c28e83SPiotr Jasiukajtis 3225c28e83SPiotr Jasiukajtis /* INDENT OFF */ 3325c28e83SPiotr Jasiukajtis /* 3425c28e83SPiotr Jasiukajtis * atanh(x) 3525c28e83SPiotr Jasiukajtis * Code originated from 4.3bsd. 3625c28e83SPiotr Jasiukajtis * Modified by K.C. Ng for SUN 4.0 libm. 3725c28e83SPiotr Jasiukajtis * Method : 3825c28e83SPiotr Jasiukajtis * 1 2x x 3925c28e83SPiotr Jasiukajtis * atanh(x) = --- * log(1 + -------) = 0.5 * log1p(2 * --------) 4025c28e83SPiotr Jasiukajtis * 2 1 - x 1 - x 4125c28e83SPiotr Jasiukajtis * Note: to guarantee atanh(-x) = -atanh(x), we use 4225c28e83SPiotr Jasiukajtis * sign(x) |x| 4325c28e83SPiotr Jasiukajtis * atanh(x) = ------- * log1p(2*-------). 4425c28e83SPiotr Jasiukajtis * 2 1 - |x| 4525c28e83SPiotr Jasiukajtis * 4625c28e83SPiotr Jasiukajtis * Special cases: 4725c28e83SPiotr Jasiukajtis * atanh(x) is NaN if |x| > 1 with signal; 4825c28e83SPiotr Jasiukajtis * atanh(NaN) is that NaN with no signal; 4925c28e83SPiotr Jasiukajtis * atanh(+-1) is +-INF with signal. 5025c28e83SPiotr Jasiukajtis */ 5125c28e83SPiotr Jasiukajtis /* INDENT ON */ 5225c28e83SPiotr Jasiukajtis 5325c28e83SPiotr Jasiukajtis #include "libm.h" 5425c28e83SPiotr Jasiukajtis #include "libm_protos.h" 5525c28e83SPiotr Jasiukajtis #include <math.h> 5625c28e83SPiotr Jasiukajtis 5725c28e83SPiotr Jasiukajtis double 5825c28e83SPiotr Jasiukajtis atanh(double x) { 5925c28e83SPiotr Jasiukajtis double t; 6025c28e83SPiotr Jasiukajtis 6125c28e83SPiotr Jasiukajtis if (isnan(x)) 6225c28e83SPiotr Jasiukajtis return (x * x); /* switched from x + x for Cheetah */ 6325c28e83SPiotr Jasiukajtis t = fabs(x); 6425c28e83SPiotr Jasiukajtis if (t > 1.0) 6525c28e83SPiotr Jasiukajtis return (_SVID_libm_err(x, x, 30)); /* sNaN */ 6625c28e83SPiotr Jasiukajtis if (t == 1.0) 6725c28e83SPiotr Jasiukajtis return (_SVID_libm_err(x, x, 31)); /* x/0; */ 6825c28e83SPiotr Jasiukajtis t = t / (1.0 - t); 6925c28e83SPiotr Jasiukajtis return (copysign(0.5, x) * log1p(t + t)); 7025c28e83SPiotr Jasiukajtis } 71