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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
*/
/*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma weak asinh = __asinh
/* INDENT OFF */
/*
* asinh(x)
* Method :
* Based on
* asinh(x) = sign(x) * log [ |x| + sqrt(x*x+1) ]
* we have
* asinh(x) := x if 1+x*x == 1,
* := sign(x)*(log(x)+ln2)) for large |x|, else
* := sign(x)*log(2|x|+1/(|x|+sqrt(x*x+1))) if|x| > 2, else
* := sign(x)*log1p(|x|+x^2/(1+sqrt(1+x^2)))
*/
/* INDENT ON */
#include "libm_synonyms.h" /* __asinh */
#include "libm_macros.h"
#include <math.h>
static const double xxx[] = {
/* one */ 1.00000000000000000000e+00, /* 3FF00000, 00000000 */
/* ln2 */ 6.93147180559945286227e-01, /* 3FE62E42, FEFA39EF */
/* huge */ 1.00000000000000000000e+300
};
#define one xxx[0]
#define ln2 xxx[1]
#define huge xxx[2]
double
asinh(double x) {
double t, w;
int hx, ix;
hx = ((int *) &x)[HIWORD];
ix = hx & 0x7fffffff;
if (ix >= 0x7ff00000)
#if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
return (ix >= 0x7ff80000 ? x : x + x);
/* assumes sparc-like QNaN */
#else
return (x + x); /* x is inf or NaN */
#endif
if (ix < 0x3e300000) { /* |x|<2**-28 */
if (huge + x > one)
return (x); /* return x inexact except 0 */
}
if (ix > 0x41b00000) { /* |x| > 2**28 */
w = log(fabs(x)) + ln2;
} else if (ix > 0x40000000) {
/* 2**28 > |x| > 2.0 */
t = fabs(x);
w = log(2.0 * t + one / (sqrt(x * x + one) + t));
} else {
/* 2.0 > |x| > 2**-28 */
t = x * x;
w = log1p(fabs(x) + t / (one + sqrt(one + t)));
}
return (hx > 0 ? w : -w);
}
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