|
111
|
1 /* Compute complex base 10 logarithm for complex __float128.
|
|
|
2 Copyright (C) 1997-2012 Free Software Foundation, Inc.
|
|
|
3 This file is part of the GNU C Library.
|
|
|
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
|
|
|
5
|
|
|
6 The GNU C Library is free software; you can redistribute it and/or
|
|
|
7 modify it under the terms of the GNU Lesser General Public
|
|
|
8 License as published by the Free Software Foundation; either
|
|
|
9 version 2.1 of the License, or (at your option) any later version.
|
|
|
10
|
|
|
11 The GNU C Library is distributed in the hope that it will be useful,
|
|
|
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
|
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
|
14 Lesser General Public License for more details.
|
|
|
15
|
|
|
16 You should have received a copy of the GNU Lesser General Public
|
|
|
17 License along with the GNU C Library; if not, see
|
|
|
18 <http://www.gnu.org/licenses/>. */
|
|
|
19
|
|
|
20 #include "quadmath-imp.h"
|
|
|
21
|
|
|
22
|
|
|
23 /* log_10 (2). */
|
|
|
24 #define M_LOG10_2q 0.3010299956639811952137388947244930267682Q
|
|
|
25
|
|
|
26
|
|
|
27 __complex128
|
|
|
28 clog10q (__complex128 x)
|
|
|
29 {
|
|
|
30 __complex128 result;
|
|
|
31 int rcls = fpclassifyq (__real__ x);
|
|
|
32 int icls = fpclassifyq (__imag__ x);
|
|
|
33
|
|
|
34 if (__builtin_expect (rcls == QUADFP_ZERO && icls == QUADFP_ZERO, 0))
|
|
|
35 {
|
|
|
36 /* Real and imaginary part are 0.0. */
|
|
|
37 __imag__ result = signbitq (__real__ x) ? M_PIq : 0.0Q;
|
|
|
38 __imag__ result = copysignq (__imag__ result, __imag__ x);
|
|
|
39 /* Yes, the following line raises an exception. */
|
|
|
40 __real__ result = -1.0Q / fabsq (__real__ x);
|
|
|
41 }
|
|
|
42 else if (__builtin_expect (rcls != QUADFP_NAN && icls != QUADFP_NAN, 1))
|
|
|
43 {
|
|
|
44 /* Neither real nor imaginary part is NaN. */
|
|
|
45 __float128 absx = fabsq (__real__ x), absy = fabsq (__imag__ x);
|
|
|
46 int scale = 0;
|
|
|
47
|
|
|
48 if (absx < absy)
|
|
|
49 {
|
|
|
50 __float128 t = absx;
|
|
|
51 absx = absy;
|
|
|
52 absy = t;
|
|
|
53 }
|
|
|
54
|
|
|
55 if (absx > FLT128_MAX / 2.0Q)
|
|
|
56 {
|
|
|
57 scale = -1;
|
|
|
58 absx = scalbnq (absx, scale);
|
|
|
59 absy = (absy >= FLT128_MIN * 2.0Q ? scalbnq (absy, scale) : 0.0Q);
|
|
|
60 }
|
|
|
61 else if (absx < FLT128_MIN && absy < FLT128_MIN)
|
|
|
62 {
|
|
|
63 scale = FLT128_MANT_DIG;
|
|
|
64 absx = scalbnq (absx, scale);
|
|
|
65 absy = scalbnq (absy, scale);
|
|
|
66 }
|
|
|
67
|
|
|
68 if (absx == 1.0Q && scale == 0)
|
|
|
69 {
|
|
|
70 __float128 absy2 = absy * absy;
|
|
|
71 if (absy2 <= FLT128_MIN * 2.0Q * M_LN10q)
|
|
|
72 __real__ result
|
|
|
73 = (absy2 / 2.0Q - absy2 * absy2 / 4.0Q) * M_LOG10Eq;
|
|
|
74 else
|
|
|
75 __real__ result = log1pq (absy2) * (M_LOG10Eq / 2.0Q);
|
|
|
76 }
|
|
|
77 else if (absx > 1.0Q && absx < 2.0Q && absy < 1.0Q && scale == 0)
|
|
|
78 {
|
|
|
79 __float128 d2m1 = (absx - 1.0Q) * (absx + 1.0Q);
|
|
|
80 if (absy >= FLT128_EPSILON)
|
|
|
81 d2m1 += absy * absy;
|
|
|
82 __real__ result = log1pq (d2m1) * (M_LOG10Eq / 2.0Q);
|
|
|
83 }
|
|
|
84 else if (absx < 1.0Q
|
|
|
85 && absx >= 0.75Q
|
|
|
86 && absy < FLT128_EPSILON / 2.0Q
|
|
|
87 && scale == 0)
|
|
|
88 {
|
|
|
89 __float128 d2m1 = (absx - 1.0Q) * (absx + 1.0Q);
|
|
|
90 __real__ result = log1pq (d2m1) * (M_LOG10Eq / 2.0Q);
|
|
|
91 }
|
|
|
92 else if (absx < 1.0Q && (absx >= 0.75Q || absy >= 0.5Q) && scale == 0)
|
|
|
93 {
|
|
|
94 __float128 d2m1 = __quadmath_x2y2m1q (absx, absy);
|
|
|
95 __real__ result = log1pq (d2m1) * (M_LOG10Eq / 2.0Q);
|
|
|
96 }
|
|
|
97 else
|
|
|
98 {
|
|
|
99 __float128 d = hypotq (absx, absy);
|
|
|
100 __real__ result = log10q (d) - scale * M_LOG10_2q;
|
|
|
101 }
|
|
|
102
|
|
|
103 __imag__ result = M_LOG10Eq * atan2q (__imag__ x, __real__ x);
|
|
|
104 }
|
|
|
105 else
|
|
|
106 {
|
|
|
107 __imag__ result = nanq ("");
|
|
|
108 if (rcls == QUADFP_INFINITE || icls == QUADFP_INFINITE)
|
|
|
109 /* Real or imaginary part is infinite. */
|
|
|
110 __real__ result = HUGE_VALQ;
|
|
|
111 else
|
|
|
112 __real__ result = nanq ("");
|
|
|
113 }
|
|
|
114
|
|
|
115 return result;
|
|
|
116 }
|
