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1
2//
3// atanh
4//
5// by Ian Ollmann
6//
7// based on MathLib v3
8//
9// Copyright � 2005, Apple Computer, Inc. All Rights Reserved.
10//
11
12#include "math.h"
13
14double atanh( double x )
15{
16 if( x != x ) return x + x;
17
18 double fabsx = __builtin_fabs( x );
19
20 if( fabsx > 1.0)
21 return sqrt( -fabsx );
22
23 if( fabsx >= 0x1.0p-27 ) //sqrt( negative epsilon )
24 {
25 fabsx = 0.5 * log1p( (fabsx + fabsx) / (1.0 - fabsx) );
26
27 }
28 else
29 {
30 if( x == 0.0 )
31 return x;
32
33 fabsx *= 0x1.0p55;
34 fabsx += 0x1.0p-1022;
35 fabsx *= 0x1.0p-55;
36 }
37
38 if( x < 0 )
39 fabsx = -fabsx;
40
41 return fabsx;
42}
43
44long double atanhl( long double x )
45{
46 if( x != x ) return x + x;
47
48 long double fabsx = __builtin_fabsl( x );
49
50 if( fabsx > 1.0L)
51 return sqrtl( -fabsx );
52
53 if( fabsx >= 0x1.0p-32 ) //sqrt( negative epsilon )
54 {
55 fabsx = 0.5 * log1pl( (fabsx + fabsx) / (1.0L - fabsx) );
56
57 }
58 else
59 {
60 if( x == 0.0 )
61 return x;
62
63 fabsx *= 0x1.0p65;
64 fabsx += 0x1.0p-16382L;
65 fabsx *= 0x1.0p-65;
66 }
67
68 if( x < 0 )
69 fabsx = -fabsx;
70
71 return fabsx;
72}
73