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/* Test of cbrt*() function family.
Copyright (C) 2012-2023 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_(32.0) * RANDOM[i] - L_(16.0); /* -16.0 <= x <= 16.0 */
DOUBLE y = CBRT (x);
DOUBLE err = y * y * y - x;
ASSERT (err > - L_(4.0) * L_(16.0) / TWO_MANT_DIG
&& err < L_(4.0) * L_(16.0) / TWO_MANT_DIG);
}
for (i = 0; i < SIZEOF (RANDOM) / 5; i++)
for (j = 0; j < SIZEOF (RANDOM) / 5; j++)
{
DOUBLE x = L_(32.0) * RANDOM[i] - L_(16.0); /* -16.0 <= x <= 16.0 */
DOUBLE y = L_(32.0) * RANDOM[j] - L_(16.0); /* -16.0 <= 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 = CBRT (x) * CBRT (y) * CBRT (z);
ASSERT (p > L_(1.0) - L_(8.0) / TWO_MANT_DIG
&& p < L_(1.0) + L_(8.0) / TWO_MANT_DIG);
}
}
}
volatile DOUBLE x;
DOUBLE y;
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