rtld: increase TLS storage space (bug 2566)
[dragonfly.git] / lib / libm / src / e_acosh.c
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1
2/* @(#)e_acosh.c 1.3 95/01/18 */
3/* $FreeBSD: head/lib/msun/src/e_acosh.c 176451 2008-02-22 02:30:36Z das $ */
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4/*
5 * ====================================================
6 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
7 *
6ff43c94 8 * Developed at SunSoft, a Sun Microsystems, Inc. business.
b34b60bc 9 * Permission to use, copy, modify, and distribute this
6ff43c94 10 * software is freely granted, provided that this notice
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11 * is preserved.
12 * ====================================================
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13 */
14
6ff43c94 15/* __ieee754_acosh(x)
b34b60bc 16 * Method :
6ff43c94 17 * Based on
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18 * acosh(x) = log [ x + sqrt(x*x-1) ]
19 * we have
20 * acosh(x) := log(x)+ln2, if x is large; else
21 * acosh(x) := log(2x-1/(sqrt(x*x-1)+x)) if x>2; else
22 * acosh(x) := log1p(t+sqrt(2.0*t+t*t)); where t=x-1.
23 *
24 * Special cases:
25 * acosh(x) is NaN with signal if x<1.
26 * acosh(NaN) is NaN without signal.
27 */
28
6ff43c94 29#include "math.h"
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30#include "math_private.h"
31
32static const double
33one = 1.0,
34ln2 = 6.93147180559945286227e-01; /* 0x3FE62E42, 0xFEFA39EF */
35
36double
6ff43c94 37__ieee754_acosh(double x)
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38{
39 double t;
40 int32_t hx;
41 u_int32_t lx;
42 EXTRACT_WORDS(hx,lx,x);
43 if(hx<0x3ff00000) { /* x < 1 */
44 return (x-x)/(x-x);
45 } else if(hx >=0x41b00000) { /* x > 2**28 */
46 if(hx >=0x7ff00000) { /* x is inf of NaN */
47 return x+x;
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48 } else
49 return __ieee754_log(x)+ln2; /* acosh(huge)=log(2x) */
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50 } else if(((hx-0x3ff00000)|lx)==0) {
51 return 0.0; /* acosh(1) = 0 */
52 } else if (hx > 0x40000000) { /* 2**28 > x > 2 */
53 t=x*x;
6ff43c94 54 return __ieee754_log(2.0*x-one/(x+sqrt(t-one)));
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55 } else { /* 1<x<2 */
56 t = x-one;
57 return log1p(t+sqrt(2.0*t+t*t));
58 }
59}