Mercurial > hg > CbC > CbC_gcc
comparison libquadmath/math/acoshq.c @ 68:561a7518be6b
update gcc-4.6
author | Nobuyasu Oshiro <dimolto@cr.ie.u-ryukyu.ac.jp> |
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date | Sun, 21 Aug 2011 07:07:55 +0900 |
parents | |
children | 04ced10e8804 |
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67:f6334be47118 | 68:561a7518be6b |
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1 /* e_acoshl.c -- long double version of e_acosh.c. | |
2 * Conversion to long double by Jakub Jelinek, jj@ultra.linux.cz. | |
3 */ | |
4 | |
5 /* | |
6 * ==================================================== | |
7 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. | |
8 * | |
9 * Developed at SunPro, a Sun Microsystems, Inc. business. | |
10 * Permission to use, copy, modify, and distribute this | |
11 * software is freely granted, provided that this notice | |
12 * is preserved. | |
13 * ==================================================== | |
14 */ | |
15 | |
16 /* __ieee754_acoshl(x) | |
17 * Method : | |
18 * Based on | |
19 * acoshl(x) = logl [ x + sqrtl(x*x-1) ] | |
20 * we have | |
21 * acoshl(x) := logl(x)+ln2, if x is large; else | |
22 * acoshl(x) := logl(2x-1/(sqrtl(x*x-1)+x)) if x>2; else | |
23 * acoshl(x) := log1pl(t+sqrtl(2.0*t+t*t)); where t=x-1. | |
24 * | |
25 * Special cases: | |
26 * acoshl(x) is NaN with signal if x<1. | |
27 * acoshl(NaN) is NaN without signal. | |
28 */ | |
29 | |
30 #include "quadmath-imp.h" | |
31 | |
32 static const __float128 | |
33 one = 1.0Q, | |
34 ln2 = 0.6931471805599453094172321214581766Q; | |
35 | |
36 __float128 | |
37 acoshq (__float128 x) | |
38 { | |
39 __float128 t; | |
40 uint64_t lx; | |
41 int64_t hx; | |
42 GET_FLT128_WORDS64(hx,lx,x); | |
43 if(hx<0x3fff000000000000LL) { /* x < 1 */ | |
44 return (x-x)/(x-x); | |
45 } else if(hx >=0x4035000000000000LL) { /* x > 2**54 */ | |
46 if(hx >=0x7fff000000000000LL) { /* x is inf of NaN */ | |
47 return x+x; | |
48 } else | |
49 return logq(x)+ln2; /* acoshl(huge)=logl(2x) */ | |
50 } else if(((hx-0x3fff000000000000LL)|lx)==0) { | |
51 return 0.0Q; /* acosh(1) = 0 */ | |
52 } else if (hx > 0x4000000000000000LL) { /* 2**28 > x > 2 */ | |
53 t=x*x; | |
54 return logq(2.0Q*x-one/(x+sqrtq(t-one))); | |
55 } else { /* 1<x<2 */ | |
56 t = x-one; | |
57 return log1pq(t+sqrtq(2.0Q*t+t*t)); | |
58 } | |
59 } |