Mercurial > gnulib
annotate tests/test-log2.h @ 40057:b06060465f09
maint: Run 'make update-copyright'
| author | Paul Eggert <eggert@cs.ucla.edu> |
|---|---|
| date | Tue, 01 Jan 2019 00:25:11 +0100 |
| parents | 10eb9086bea0 |
| children |
| rev | line source |
|---|---|
| 16677 | 1 /* Test of log2*() function family. |
|
40057
b06060465f09
maint: Run 'make update-copyright'
Paul Eggert <eggert@cs.ucla.edu>
parents:
19484
diff
changeset
|
2 Copyright (C) 2012-2019 Free Software Foundation, Inc. |
| 16677 | 3 |
| 4 This program is free software: you can redistribute it and/or modify | |
| 5 it under the terms of the GNU General Public License as published by | |
| 6 the Free Software Foundation; either version 3 of the License, or | |
| 7 (at your option) any later version. | |
| 8 | |
| 9 This program is distributed in the hope that it will be useful, | |
| 10 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 12 GNU General Public License for more details. | |
| 13 | |
| 14 You should have received a copy of the GNU General Public License | |
| 19190 | 15 along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
| 16677 | 16 |
| 17 static void | |
| 18 test_function (void) | |
| 19 { | |
| 20 int i; | |
| 21 int j; | |
| 22 const DOUBLE TWO_MANT_DIG = | |
| 23 /* Assume MANT_DIG <= 5 * 31. | |
| 24 Use the identity | |
| 25 n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5). */ | |
| 26 (DOUBLE) (1U << ((MANT_DIG - 1) / 5)) | |
| 27 * (DOUBLE) (1U << ((MANT_DIG - 1 + 1) / 5)) | |
| 28 * (DOUBLE) (1U << ((MANT_DIG - 1 + 2) / 5)) | |
| 29 * (DOUBLE) (1U << ((MANT_DIG - 1 + 3) / 5)) | |
| 30 * (DOUBLE) (1U << ((MANT_DIG - 1 + 4) / 5)); | |
| 31 | |
| 32 /* Pole. */ | |
| 33 ASSERT (LOG2 (L_(0.0)) == - HUGEVAL); | |
| 34 ASSERT (LOG2 (MINUS_ZERO) == - HUGEVAL); | |
| 35 | |
| 36 /* Integral values. */ | |
| 37 { | |
| 38 DOUBLE x = L_(1.0); | |
| 39 DOUBLE y = LOG2 (x); | |
| 40 ASSERT (y == L_(0.0)); | |
| 41 } | |
| 42 { | |
| 43 int e; | |
| 44 DOUBLE x; | |
| 45 DOUBLE y; | |
| 46 for (e = 0, x = L_(0.0), y = L_(1.0); | |
| 47 e <= MAX_EXP - 1; | |
| 48 e++, x = x + L_(1.0), y = y * L_(2.0)) | |
| 49 { | |
| 50 /* Invariant: x = e, y = 2^e. */ | |
| 51 DOUBLE z = LOG2 (y); | |
| 52 ASSERT (z == x); | |
| 53 } | |
| 54 } | |
| 55 { | |
| 56 int e; | |
| 57 DOUBLE x; | |
| 58 DOUBLE y; | |
| 59 for (e = 0, x = L_(0.0), y = L_(1.0); | |
| 60 e >= MIN_EXP - 1; | |
| 61 e--, x = x - L_(1.0), y = y * L_(0.5)) | |
| 62 { | |
| 63 /* Invariant: x = e, y = 2^e. */ | |
| 64 DOUBLE z = LOG2 (y); | |
| 65 ASSERT (z == x); | |
| 66 } | |
| 67 } | |
| 68 | |
| 69 /* Randomized tests. */ | |
| 70 { | |
| 71 /* Error bound, in ulps. */ | |
| 72 const DOUBLE err_bound = | |
| 73 (sizeof (DOUBLE) > sizeof (double) ? | |
| 74 #if defined __i386__ && defined __FreeBSD__ | |
| 75 /* On FreeBSD/x86 6.4, the 'long double' type really has only 53 bits of | |
| 76 precision in the compiler but 64 bits of precision at runtime. See | |
|
19439
8bfc20b57265
maint: shorten https://lists.gnu.org/archive/html/... links
Jim Meyering <meyering@fb.com>
parents:
19192
diff
changeset
|
77 <https://lists.gnu.org/r/bug-gnulib/2008-07/msg00063.html>. |
| 16677 | 78 The compiler has truncated all 'long double' literals in log2l.c to |
| 79 53 bits of precision. */ | |
| 80 L_(8193.0) | |
| 81 #else | |
| 82 L_(5.0) | |
| 83 #endif | |
| 84 : L_(5.0)); | |
| 85 | |
| 86 for (i = 0; i < SIZEOF (RANDOM); i++) | |
| 87 { | |
| 88 DOUBLE x = L_(16.0) * RANDOM[i] + L_(1.0); /* 1.0 <= x <= 17.0 */ | |
| 89 DOUBLE y = LOG2 (x); | |
| 90 DOUBLE z = LOG2 (L_(1.0) / x); | |
| 91 DOUBLE err = y + z; | |
| 92 ASSERT (y >= L_(0.0)); | |
| 93 ASSERT (z <= L_(0.0)); | |
| 94 ASSERT (err > - err_bound / TWO_MANT_DIG | |
| 95 && err < err_bound / TWO_MANT_DIG); | |
| 96 } | |
| 97 } | |
| 98 | |
| 99 { | |
| 100 /* Error bound, in ulps. */ | |
| 101 const DOUBLE err_bound = | |
| 102 (sizeof (DOUBLE) > sizeof (double) ? | |
| 103 #if defined __i386__ && defined __FreeBSD__ | |
| 104 /* On FreeBSD/x86 6.4, the 'long double' type really has only 53 bits of | |
| 105 precision in the compiler but 64 bits of precision at runtime. See | |
|
19439
8bfc20b57265
maint: shorten https://lists.gnu.org/archive/html/... links
Jim Meyering <meyering@fb.com>
parents:
19192
diff
changeset
|
106 <https://lists.gnu.org/r/bug-gnulib/2008-07/msg00063.html>. |
| 16677 | 107 The compiler has truncated all 'long double' literals in log2l.c to |
| 108 53 bits of precision. */ | |
| 109 L_(8193.0) | |
| 110 #else | |
| 111 L_(9.0) | |
| 112 #endif | |
| 113 : L_(9.0)); | |
| 114 | |
| 115 for (i = 0; i < SIZEOF (RANDOM) / 5; i++) | |
| 116 for (j = 0; j < SIZEOF (RANDOM) / 5; j++) | |
| 117 { | |
| 118 DOUBLE x = L_(17.0) / (L_(16.0) - L_(15.0) * RANDOM[i]) - L_(1.0); | |
| 119 DOUBLE y = L_(17.0) / (L_(16.0) - L_(15.0) * RANDOM[j]) - L_(1.0); | |
| 120 /* 1/16 <= x,y <= 16 */ | |
| 121 DOUBLE z = L_(1.0) / (x * y); | |
| 122 /* Approximately x * y * z = 1. */ | |
| 123 DOUBLE err = LOG2 (x) + LOG2 (y) + LOG2 (z); | |
| 124 ASSERT (err > - err_bound / TWO_MANT_DIG | |
| 125 && err < err_bound / TWO_MANT_DIG); | |
| 126 } | |
| 127 } | |
| 128 } | |
| 129 | |
| 130 volatile DOUBLE x; | |
| 131 DOUBLE y; |