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101 lines
3.4 KiB
C
101 lines
3.4 KiB
C
/* Test of log1p*() function family.
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Copyright (C) 2012-2017 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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static void
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test_function (void)
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{
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int i;
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int j;
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const DOUBLE TWO_MANT_DIG =
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/* Assume MANT_DIG <= 5 * 31.
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Use the identity
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n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5). */
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(DOUBLE) (1U << ((MANT_DIG - 1) / 5))
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* (DOUBLE) (1U << ((MANT_DIG - 1 + 1) / 5))
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* (DOUBLE) (1U << ((MANT_DIG - 1 + 2) / 5))
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* (DOUBLE) (1U << ((MANT_DIG - 1 + 3) / 5))
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* (DOUBLE) (1U << ((MANT_DIG - 1 + 4) / 5));
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/* Pole. */
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{
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DOUBLE z = LOG1P (L_(-1.0));
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ASSERT (z == - HUGEVAL);
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}
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/* Randomized tests. */
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{
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/* Error bound, in ulps. */
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const DOUBLE err_bound =
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(sizeof (DOUBLE) > sizeof (double) ?
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#if defined __i386__ && defined __FreeBSD__
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/* On FreeBSD/x86 6.4, the 'long double' type really has only 53 bits of
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precision in the compiler but 64 bits of precision at runtime. See
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<http://lists.gnu.org/archive/html/bug-gnulib/2008-07/msg00063.html>.
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The compiler has truncated all 'long double' literals in log1pl.c to
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53 bits of precision. */
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L_(900.0)
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#else
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L_(26.0)
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#endif
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: L_(13.0));
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for (i = 0; i < SIZEOF (RANDOM); i++)
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{
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DOUBLE x = L_(16.0) * RANDOM[i]; /* 0.0 <= x <= 16.0 */
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DOUBLE y = LOG1P (x);
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DOUBLE z = LOG1P (- x / (L_(1.0) + x));
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DOUBLE err = y + z;
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ASSERT (y >= L_(0.0));
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ASSERT (z <= L_(0.0));
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ASSERT (err > - err_bound / TWO_MANT_DIG
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&& err < err_bound / TWO_MANT_DIG);
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}
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}
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{
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/* Error bound, in ulps. */
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const DOUBLE err_bound =
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(sizeof (DOUBLE) > sizeof (double) ?
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#if defined __i386__ && defined __FreeBSD__
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/* On FreeBSD/x86 6.4, the 'long double' type really has only 53 bits of
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precision in the compiler but 64 bits of precision at runtime. See
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<http://lists.gnu.org/archive/html/bug-gnulib/2008-07/msg00063.html>.
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The compiler has truncated all 'long double' literals in log1pl.c to
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53 bits of precision. */
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L_(1020.0)
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#else
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L_(65.0)
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#endif
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: L_(61.0));
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for (i = 0; i < SIZEOF (RANDOM) / 5; i++)
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for (j = 0; j < SIZEOF (RANDOM) / 5; j++)
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{
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DOUBLE x = L_(17.0) / (L_(16.0) - L_(15.0) * RANDOM[i]) - L_(2.0);
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DOUBLE y = L_(17.0) / (L_(16.0) - L_(15.0) * RANDOM[j]) - L_(2.0);
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/* -15/16 <= x,y <= 15 */
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DOUBLE z = L_(1.0) / ((L_(1.0) + x) * (L_(1.0) + y)) - L_(1.0);
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/* Approximately (1+x) * (1+y) * (1+z) = 1. */
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DOUBLE err = LOG1P (x) + LOG1P (y) + LOG1P (z);
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ASSERT (err > - err_bound / TWO_MANT_DIG
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&& err < err_bound / TWO_MANT_DIG);
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}
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}
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}
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volatile DOUBLE x;
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DOUBLE y;
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