Chromium Code Reviews
chromiumcodereview-hr@appspot.gserviceaccount.com (chromiumcodereview-hr) | Please choose your nickname with Settings | Help | Chromium Project | Gerrit Changes | Sign out
(277)

Side by Side Diff: fusl/src/math/log2l.c

Issue 1714623002: [fusl] clang-format fusl (Closed) Base URL: git@github.com:domokit/mojo.git@master
Patch Set: headers too Created 4 years, 10 months ago
Use n/p to move between diff chunks; N/P to move between comments. Draft comments are only viewable by you.
Jump to:
View unified diff | Download patch
OLDNEW
1 /* origin: OpenBSD /usr/src/lib/libm/src/ld80/e_log2l.c */ 1 /* origin: OpenBSD /usr/src/lib/libm/src/ld80/e_log2l.c */
2 /* 2 /*
3 * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net> 3 * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net>
4 * 4 *
5 * Permission to use, copy, modify, and distribute this software for any 5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above 6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies. 7 * copyright notice and this permission notice appear in all copies.
8 * 8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
(...skipping 37 matching lines...) Expand 10 before | Expand all | Expand 10 after
48 * IEEE exp(+-10000) 70000 5.4e-20 2.3e-20 48 * IEEE exp(+-10000) 70000 5.4e-20 2.3e-20
49 * 49 *
50 * In the tests over the interval exp(+-10000), the logarithms 50 * In the tests over the interval exp(+-10000), the logarithms
51 * of the random arguments were uniformly distributed over 51 * of the random arguments were uniformly distributed over
52 * [-10000, +10000]. 52 * [-10000, +10000].
53 */ 53 */
54 54
55 #include "libm.h" 55 #include "libm.h"
56 56
57 #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024 57 #if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
58 long double log2l(long double x) 58 long double log2l(long double x) {
59 { 59 return log2(x);
60 » return log2(x);
61 } 60 }
62 #elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384 61 #elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
63 /* Coefficients for ln(1+x) = x - x**2/2 + x**3 P(x)/Q(x) 62 /* Coefficients for ln(1+x) = x - x**2/2 + x**3 P(x)/Q(x)
64 * 1/sqrt(2) <= x < sqrt(2) 63 * 1/sqrt(2) <= x < sqrt(2)
65 * Theoretical peak relative error = 6.2e-22 64 * Theoretical peak relative error = 6.2e-22
66 */ 65 */
67 static const long double P[] = { 66 static const long double P[] = {
68 4.9962495940332550844739E-1L, 67 4.9962495940332550844739E-1L, 1.0767376367209449010438E1L,
69 1.0767376367209449010438E1L, 68 7.7671073698359539859595E1L, 2.5620629828144409632571E2L,
70 7.7671073698359539859595E1L, 69 4.2401812743503691187826E2L, 3.4258224542413922935104E2L,
71 2.5620629828144409632571E2L, 70 1.0747524399916215149070E2L,
72 4.2401812743503691187826E2L,
73 3.4258224542413922935104E2L,
74 1.0747524399916215149070E2L,
75 }; 71 };
76 static const long double Q[] = { 72 static const long double Q[] = {
77 /* 1.0000000000000000000000E0,*/ 73 /* 1.0000000000000000000000E0,*/
78 2.3479774160285863271658E1L, 74 2.3479774160285863271658E1L, 1.9444210022760132894510E2L,
79 1.9444210022760132894510E2L, 75 7.7952888181207260646090E2L, 1.6911722418503949084863E3L,
80 7.7952888181207260646090E2L, 76 2.0307734695595183428202E3L, 1.2695660352705325274404E3L,
81 1.6911722418503949084863E3L, 77 3.2242573199748645407652E2L,
82 2.0307734695595183428202E3L,
83 1.2695660352705325274404E3L,
84 3.2242573199748645407652E2L,
85 }; 78 };
86 79
87 /* Coefficients for log(x) = z + z^3 P(z^2)/Q(z^2), 80 /* Coefficients for log(x) = z + z^3 P(z^2)/Q(z^2),
88 * where z = 2(x-1)/(x+1) 81 * where z = 2(x-1)/(x+1)
89 * 1/sqrt(2) <= x < sqrt(2) 82 * 1/sqrt(2) <= x < sqrt(2)
90 * Theoretical peak relative error = 6.16e-22 83 * Theoretical peak relative error = 6.16e-22
91 */ 84 */
92 static const long double R[4] = { 85 static const long double R[4] = {
93 1.9757429581415468984296E-3L, 86 1.9757429581415468984296E-3L, -7.1990767473014147232598E-1L,
94 -7.1990767473014147232598E-1L, 87 1.0777257190312272158094E1L, -3.5717684488096787370998E1L,
95 1.0777257190312272158094E1L,
96 -3.5717684488096787370998E1L,
97 }; 88 };
98 static const long double S[4] = { 89 static const long double S[4] = {
99 /* 1.00000000000000000000E0L,*/ 90 /* 1.00000000000000000000E0L,*/
100 -2.6201045551331104417768E1L, 91 -2.6201045551331104417768E1L, 1.9361891836232102174846E2L,
101 1.9361891836232102174846E2L, 92 -4.2861221385716144629696E2L,
102 -4.2861221385716144629696E2L,
103 }; 93 };
104 /* log2(e) - 1 */ 94 /* log2(e) - 1 */
105 #define LOG2EA 4.4269504088896340735992e-1L 95 #define LOG2EA 4.4269504088896340735992e-1L
106 96
107 #define SQRTH 0.70710678118654752440L 97 #define SQRTH 0.70710678118654752440L
108 98
109 long double log2l(long double x) 99 long double log2l(long double x) {
110 { 100 long double y, z;
111 » long double y, z; 101 int e;
112 » int e;
113 102
114 » if (isnan(x)) 103 if (isnan(x))
115 » » return x; 104 return x;
116 » if (x == INFINITY) 105 if (x == INFINITY)
117 » » return x; 106 return x;
118 » if (x <= 0.0) { 107 if (x <= 0.0) {
119 » » if (x == 0.0) 108 if (x == 0.0)
120 » » » return -1/(x*x); /* -inf with divbyzero */ 109 return -1 / (x * x); /* -inf with divbyzero */
121 » » return 0/0.0f; /* nan with invalid */ 110 return 0 / 0.0f; /* nan with invalid */
122 » } 111 }
123 112
124 » /* separate mantissa from exponent */ 113 /* separate mantissa from exponent */
125 » /* Note, frexp is used so that denormal numbers 114 /* Note, frexp is used so that denormal numbers
126 » * will be handled properly. 115 * will be handled properly.
127 » */ 116 */
128 » x = frexpl(x, &e); 117 x = frexpl(x, &e);
129 118
130 » /* logarithm using log(x) = z + z**3 P(z)/Q(z), 119 /* logarithm using log(x) = z + z**3 P(z)/Q(z),
131 » * where z = 2(x-1)/x+1) 120 * where z = 2(x-1)/x+1)
132 » */ 121 */
133 » if (e > 2 || e < -2) { 122 if (e > 2 || e < -2) {
134 » » if (x < SQRTH) { /* 2(2x-1)/(2x+1) */ 123 if (x < SQRTH) { /* 2(2x-1)/(2x+1) */
135 » » » e -= 1; 124 e -= 1;
136 » » » z = x - 0.5; 125 z = x - 0.5;
137 » » » y = 0.5 * z + 0.5; 126 y = 0.5 * z + 0.5;
138 » » } else { /* 2 (x-1)/(x+1) */ 127 } else { /* 2 (x-1)/(x+1) */
139 » » » z = x - 0.5; 128 z = x - 0.5;
140 » » » z -= 0.5; 129 z -= 0.5;
141 » » » y = 0.5 * x + 0.5; 130 y = 0.5 * x + 0.5;
142 » » } 131 }
143 » » x = z / y; 132 x = z / y;
144 » » z = x*x; 133 z = x * x;
145 » » y = x * (z * __polevll(z, R, 3) / __p1evll(z, S, 3)); 134 y = x * (z * __polevll(z, R, 3) / __p1evll(z, S, 3));
146 » » goto done; 135 goto done;
147 » } 136 }
148 137
149 » /* logarithm using log(1+x) = x - .5x**2 + x**3 P(x)/Q(x) */ 138 /* logarithm using log(1+x) = x - .5x**2 + x**3 P(x)/Q(x) */
150 » if (x < SQRTH) { 139 if (x < SQRTH) {
151 » » e -= 1; 140 e -= 1;
152 » » x = 2.0*x - 1.0; 141 x = 2.0 * x - 1.0;
153 » } else { 142 } else {
154 » » x = x - 1.0; 143 x = x - 1.0;
155 » } 144 }
156 » z = x*x; 145 z = x * x;
157 » y = x * (z * __polevll(x, P, 6) / __p1evll(x, Q, 7)); 146 y = x * (z * __polevll(x, P, 6) / __p1evll(x, Q, 7));
158 » y = y - 0.5*z; 147 y = y - 0.5 * z;
159 148
160 done: 149 done:
161 » /* Multiply log of fraction by log2(e) 150 /* Multiply log of fraction by log2(e)
162 » * and base 2 exponent by 1 151 * and base 2 exponent by 1
163 » * 152 *
164 » * ***CAUTION*** 153 * ***CAUTION***
165 » * 154 *
166 » * This sequence of operations is critical and it may 155 * This sequence of operations is critical and it may
167 » * be horribly defeated by some compiler optimizers. 156 * be horribly defeated by some compiler optimizers.
168 » */ 157 */
169 » z = y * LOG2EA; 158 z = y * LOG2EA;
170 » z += x * LOG2EA; 159 z += x * LOG2EA;
171 » z += y; 160 z += y;
172 » z += x; 161 z += x;
173 » z += e; 162 z += e;
174 » return z; 163 return z;
175 } 164 }
176 #elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384 165 #elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
177 // TODO: broken implementation to make things compile 166 // TODO: broken implementation to make things compile
178 long double log2l(long double x) 167 long double log2l(long double x) {
179 { 168 return log2(x);
180 » return log2(x);
181 } 169 }
182 #endif 170 #endif
OLDNEW

Powered by Google App Engine
This is Rietveld 408576698