| /* Test of expm1*() function family. |
| Copyright (C) 2012-2020 Free Software Foundation, Inc. |
| |
| This program is free software: you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
| |
| static void |
| test_function (void) |
| { |
| int i; |
| int j; |
| const DOUBLE TWO_MANT_DIG = |
| /* Assume MANT_DIG <= 5 * 31. |
| Use the identity |
| n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5). */ |
| (DOUBLE) (1U << ((MANT_DIG - 1) / 5)) |
| * (DOUBLE) (1U << ((MANT_DIG - 1 + 1) / 5)) |
| * (DOUBLE) (1U << ((MANT_DIG - 1 + 2) / 5)) |
| * (DOUBLE) (1U << ((MANT_DIG - 1 + 3) / 5)) |
| * (DOUBLE) (1U << ((MANT_DIG - 1 + 4) / 5)); |
| |
| /* Arguments near zero. */ |
| { |
| DOUBLE x; |
| |
| for (i = -1, x = L_(0.5); i >= MIN_EXP; i--, x *= L_(0.5)) |
| { |
| DOUBLE y; |
| |
| y = EXPM1 (x); |
| #ifdef __MINGW32__ /* mingw returns a value that is slightly too small. */ |
| ASSERT (y >= x * (L_(1.0) - L_(1.0) / TWO_MANT_DIG)); |
| #else |
| ASSERT (y >= x); |
| #endif |
| ASSERT (y < L_(1.5) * x); |
| |
| y = EXPM1 (- x); |
| ASSERT (y >= - x); |
| ASSERT (y < - L_(0.5) * x); |
| } |
| } |
| |
| /* Randomized tests. */ |
| { |
| /* Error bound, in ulps. */ |
| const DOUBLE err_bound = |
| (sizeof (DOUBLE) > sizeof (double) ? |
| #if defined __i386__ && defined __FreeBSD__ |
| /* On FreeBSD/x86 6.4, the 'long double' type really has only 53 bits of |
| precision in the compiler but 64 bits of precision at runtime. See |
| <https://lists.gnu.org/r/bug-gnulib/2008-07/msg00063.html>. |
| The compiler has truncated all 'long double' literals in expl.c to |
| 53 bits of precision. */ |
| L_(1024.0) |
| #else |
| L_(5.0) |
| #endif |
| : L_(5.0)); |
| |
| for (i = 0; i < SIZEOF (RANDOM); i++) |
| { |
| DOUBLE x = L_(2.0) * RANDOM[i]; /* 0.0 <= x <= 2.0 */ |
| DOUBLE y = EXPM1 (x); |
| DOUBLE z = EXPM1 (- x); |
| DOUBLE err = y + (1 + y) * z; |
| ASSERT (y >= L_(0.0)); |
| ASSERT (z <= L_(0.0)); |
| ASSERT (err > - err_bound / TWO_MANT_DIG |
| && err < err_bound / TWO_MANT_DIG); |
| } |
| } |
| |
| { |
| /* Error bound, in ulps. */ |
| const DOUBLE err_bound = |
| (sizeof (DOUBLE) > sizeof (double) ? |
| #if defined __i386__ && defined __FreeBSD__ |
| L_(1536.0) |
| #else |
| L_(11.0) |
| #endif |
| : L_(9.0)); |
| |
| for (i = 0; i < SIZEOF (RANDOM) / 5; i++) |
| for (j = 0; j < SIZEOF (RANDOM) / 5; j++) |
| { |
| DOUBLE x = L_(2.0) * RANDOM[i] - L_(1.0); /* -1.0 <= x <= 1.0 */ |
| DOUBLE y = L_(2.0) * RANDOM[j] - L_(1.0); /* -1.0 <= y <= 1.0 */ |
| DOUBLE z = - x - y; |
| /* Approximately x + y + z = 0. */ |
| { |
| DOUBLE a = EXPM1 (x); |
| DOUBLE b = EXPM1 (y); |
| DOUBLE c = EXPM1 (z); |
| DOUBLE err = a + (1 + a) * (b + (1 + b) * c); |
| ASSERT (err > - err_bound / TWO_MANT_DIG |
| && err < err_bound / TWO_MANT_DIG); |
| } |
| } |
| } |
| } |
| |
| volatile DOUBLE x; |
| DOUBLE y; |