| /* Test of sqrt*() 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)); |
| |
| /* Randomized tests. */ |
| for (i = 0; i < SIZEOF (RANDOM); i++) |
| { |
| DOUBLE x = L_(16.0) * RANDOM[i]; /* 0.0 <= x <= 16.0 */ |
| DOUBLE y = SQRT (x); |
| DOUBLE err = y * y - x; |
| ASSERT (y >= L_(0.0)); |
| ASSERT (err > - L_(16.0) / TWO_MANT_DIG |
| && err < L_(16.0) / TWO_MANT_DIG); |
| } |
| |
| for (i = 0; i < SIZEOF (RANDOM) / 4; i++) |
| for (j = 0; j < SIZEOF (RANDOM) / 4; j++) |
| { |
| DOUBLE x = L_(16.0) * RANDOM[i]; /* 0.0 <= x <= 16.0 */ |
| DOUBLE y = L_(16.0) * RANDOM[j]; /* 0.0 <= y <= 16.0 */ |
| if (x > L_(0.0) && y > L_(0.0)) |
| { |
| DOUBLE z = L_(1.0) / (x * y); |
| /* Approximately x * y * z = 1. */ |
| DOUBLE p = SQRT (x) * SQRT (y) * SQRT (z); |
| ASSERT (p > L_(1.0) - L_(4.0) / TWO_MANT_DIG |
| && p < L_(1.0) + L_(4.0) / TWO_MANT_DIG); |
| } |
| } |
| } |
| |
| volatile DOUBLE x; |
| DOUBLE y; |