1 /* Test of log*() function family.
2 Copyright (C) 2012 Free Software Foundation, Inc.
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.
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.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
22 const DOUBLE TWO_MANT_DIG =
23 /* Assume MANT_DIG <= 5 * 31.
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));
33 DOUBLE z = LOG (L_(0.0));
34 ASSERT (z == - HUGEVAL);
37 DOUBLE z = LOG (MINUS_ZERO);
38 ASSERT (z == - HUGEVAL);
41 /* Randomized tests. */
43 /* Error bound, in ulps. */
44 const DOUBLE err_bound =
45 (sizeof (DOUBLE) == sizeof (long double) ?
46 #if defined __i386__ && defined __FreeBSD__
47 /* On FreeBSD/x86 6.4, the 'long double' type really has only 53 bits of
48 precision in the compiler but 64 bits of precision at runtime. See
49 <http://lists.gnu.org/archive/html/bug-gnulib/2008-07/msg00063.html>.
50 The compiler has truncated all 'long double' literals in logl.c to
51 53 bits of precision. */
58 for (i = 0; i < SIZEOF (RANDOM); i++)
60 DOUBLE x = L_(16.0) * RANDOM[i] + L_(1.0); /* 1.0 <= x <= 17.0 */
62 DOUBLE z = LOG (L_(1.0) / x);
64 ASSERT (y >= L_(0.0));
65 ASSERT (z <= L_(0.0));
66 ASSERT (err > - err_bound / TWO_MANT_DIG
67 && err < err_bound / TWO_MANT_DIG);
72 /* Error bound, in ulps. */
73 const DOUBLE err_bound =
74 (sizeof (DOUBLE) == sizeof (long double) ?
75 #if defined __i386__ && defined __FreeBSD__
76 /* On FreeBSD/x86 6.4, the 'long double' type really has only 53 bits of
77 precision in the compiler but 64 bits of precision at runtime. See
78 <http://lists.gnu.org/archive/html/bug-gnulib/2008-07/msg00063.html>.
79 The compiler has truncated all 'long double' literals in logl.c to
80 53 bits of precision. */
87 for (i = 0; i < SIZEOF (RANDOM) / 5; i++)
88 for (j = 0; j < SIZEOF (RANDOM) / 5; j++)
90 DOUBLE x = L_(17.0) / (L_(16.0) - L_(15.0) * RANDOM[i]) - L_(1.0);
91 DOUBLE y = L_(17.0) / (L_(16.0) - L_(15.0) * RANDOM[j]) - L_(1.0);
92 /* 1/16 <= x,y <= 16 */
93 DOUBLE z = L_(1.0) / (x * y);
94 /* Approximately x * y * z = 1. */
95 DOUBLE err = LOG (x) + LOG (y) + LOG (z);
96 ASSERT (err > - err_bound / TWO_MANT_DIG
97 && err < err_bound / TWO_MANT_DIG);