1 /* Test of log10*() function family. 2 Copyright (C) 2012-2020 Free Software Foundation, Inc. 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 15 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 16 17 static void test_function(void)18test_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 { 34 DOUBLE z = LOG10 (L_(0.0)); 35 ASSERT (z == - HUGEVAL); 36 } 37 { 38 DOUBLE z = LOG10 (MINUS_ZERO); 39 ASSERT (z == - HUGEVAL); 40 } 41 42 /* Randomized tests. */ 43 { 44 /* Error bound, in ulps. */ 45 const DOUBLE err_bound = 46 (sizeof (DOUBLE) > sizeof (double) ? 47 #if defined __i386__ && defined __FreeBSD__ 48 /* On FreeBSD/x86 6.4, the 'long double' type really has only 53 bits of 49 precision in the compiler but 64 bits of precision at runtime. See 50 <https://lists.gnu.org/r/bug-gnulib/2008-07/msg00063.html>. 51 The compiler has truncated all 'long double' literals in log10l.c to 52 53 bits of precision. */ 53 L_(18.0) 54 #else 55 L_(3.0) 56 #endif 57 : L_(3.0)); 58 59 for (i = 0; i < SIZEOF (RANDOM); i++) 60 { 61 DOUBLE x = L_(16.0) * RANDOM[i] + L_(1.0); /* 1.0 <= x <= 17.0 */ 62 DOUBLE y = LOG10 (x); 63 DOUBLE z = LOG10 (L_(1.0) / x); 64 DOUBLE err = y + z; 65 ASSERT (y >= L_(0.0)); 66 ASSERT (z <= L_(0.0)); 67 ASSERT (err > - err_bound / TWO_MANT_DIG 68 && err < err_bound / TWO_MANT_DIG); 69 } 70 } 71 72 { 73 /* Error bound, in ulps. */ 74 const DOUBLE err_bound = 75 (sizeof (DOUBLE) > sizeof (double) ? 76 #if defined __i386__ && defined __FreeBSD__ 77 /* On FreeBSD/x86 6.4, the 'long double' type really has only 53 bits of 78 precision in the compiler but 64 bits of precision at runtime. See 79 <https://lists.gnu.org/r/bug-gnulib/2008-07/msg00063.html>. 80 The compiler has truncated all 'long double' literals in log10l.c to 81 53 bits of precision. */ 82 L_(38.0) 83 #else 84 L_(5.0) 85 #endif 86 : L_(5.0)); 87 88 for (i = 0; i < SIZEOF (RANDOM) / 5; i++) 89 for (j = 0; j < SIZEOF (RANDOM) / 5; j++) 90 { 91 DOUBLE x = L_(17.0) / (L_(16.0) - L_(15.0) * RANDOM[i]) - L_(1.0); 92 DOUBLE y = L_(17.0) / (L_(16.0) - L_(15.0) * RANDOM[j]) - L_(1.0); 93 /* 1/16 <= x,y <= 16 */ 94 DOUBLE z = L_(1.0) / (x * y); 95 /* Approximately x * y * z = 1. */ 96 DOUBLE err = LOG10 (x) + LOG10 (y) + LOG10 (z); 97 ASSERT (err > - err_bound / TWO_MANT_DIG 98 && err < err_bound / TWO_MANT_DIG); 99 } 100 } 101 } 102 103 volatile DOUBLE x; 104 DOUBLE y; 105