25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis/*
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * CDDL HEADER START
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis *
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * The contents of this file are subject to the terms of the
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * Common Development and Distribution License (the "License").
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * You may not use this file except in compliance with the License.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis *
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * or http://www.opensolaris.org/os/licensing.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * See the License for the specific language governing permissions
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * and limitations under the License.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis *
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * When distributing Covered Code, include this CDDL HEADER in each
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * If applicable, add the following below this CDDL HEADER, with the
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * fields enclosed by brackets "[]" replaced with your own identifying
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * information: Portions Copyright [yyyy] [name of copyright owner]
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis *
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * CDDL HEADER END
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis */
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis/*
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis */
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis/*
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * Use is subject to license terms.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis */
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis
ddc0e0b53c661f6e439e3b7072b3ef353eadb4afRichard Lowe#pragma weak __cosh = cosh
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis/* INDENT OFF */
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis/*
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * cosh(x)
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * Code originated from 4.3bsd.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * Modified by K.C. Ng for SUN 4.0 libm.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * Method :
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * 1. Replace x by |x| (cosh(x) = cosh(-x)).
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * 2.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * [ exp(x) - 1 ]^2
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * 0 <= x <= 0.3465 : cosh(x) := 1 + -------------------
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * 2*exp(x)
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis *
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * exp(x) + 1/exp(x)
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * 0.3465 <= x <= 22 : cosh(x) := -------------------
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * 2
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * 22 <= x <= lnovft : cosh(x) := exp(x)/2
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * lnovft <= x < INF : cosh(x) := scalbn(exp(x-1024*ln2),1023)
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis *
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * Note: .3465 is a number near one half of ln2.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis *
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * Special cases:
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * cosh(x) is |x| if x is +INF, -INF, or NaN.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * only cosh(0)=1 is exact for finite x.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis */
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis/* INDENT ON */
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis#include "libm.h"
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtisstatic const double
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis ln2 = 6.93147180559945286227e-01,
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis ln2hi = 6.93147180369123816490e-01,
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis ln2lo = 1.90821492927058770002e-10,
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis lnovft = 7.09782712893383973096e+02;
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtisdouble
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtiscosh(double x) {
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis double t, w;
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis w = fabs(x);
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis if (!finite(w))
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis return (w * w);
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis if (w < 0.3465) {
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis t = expm1(w);
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis w = 1.0 + t;
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis if (w != 1.0)
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis w = 1.0 + (t * t) / (w + w);
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis return (w);
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis } else if (w < 22.0) {
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis t = exp(w);
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis return (0.5 * (t + 1.0 / t));
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis } else if (w <= lnovft) {
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis return (0.5 * exp(w));
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis } else {
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis w = (w - 1024 * ln2hi) - 1024 * ln2lo;
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis if (w >= ln2)
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis return (_SVID_libm_err(x, x, 5));
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis else
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis return (scalbn(exp(w), 1023));
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis }
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis}