2012-03-05 Bruno Haible <bruno@clisp.org>
+ exp* tests: More tests.
+ * tests/test-exp.h: New file.
+ * tests/test-exp.c: Include <float.h> and test-exp.h.
+ (main): Invoke test_function.
+ * tests/test-expf.c: Include <float.h> and test-exp.h.
+ (main): Invoke test_function.
+ * tests/test-expl.c: Include <float.h> and test-exp.h.
+ (main): Invoke test_function.
+ * modules/exp-tests (Files): Add tests/test-exp.h, tests/randomd.c.
+ (Makefile.am): Add randomd.c to test_exp_SOURCES.
+ * modules/expf-tests (Files): Add tests/test-exp.h, tests/randomf.c.
+ (Makefile.am): Add randomf.c to test_expf_SOURCES.
+ * modules/expl-tests (Files): Add tests/test-exp.h, tests/randoml.c.
+ (Depends-on): Add 'float'.
+ (Makefile.am): Add randoml.c to test_expl_SOURCES.
+
expl: Fix precision of computed result.
* lib/expl.c: Completely rewritten.
* modules/expl (Depends-on): Add isnanl, roundl, ldexpl. Remove floorl.
--- /dev/null
+/* Test of exp*() function family.
+ Copyright (C) 2012 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 <http://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. */
+ {
+ /* Error bound, in ulps. */
+ const DOUBLE err_bound =
+ (sizeof (DOUBLE) == sizeof (long 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
+ <http://lists.gnu.org/archive/html/bug-gnulib/2008-07/msg00063.html>.
+ The compiler has truncated all 'long double' literals in expl.c to
+ 53 bits of precision. */
+ L_(1350.0)
+#else
+ L_(4.0)
+#endif
+ : L_(2.0));
+
+ for (i = 0; i < SIZEOF (RANDOM); i++)
+ {
+ DOUBLE x = L_(16.0) * RANDOM[i]; /* 0.0 <= x <= 16.0 */
+ DOUBLE y = EXP (x);
+ DOUBLE z = EXP (- x);
+ DOUBLE err = y * z - L_(1.0);
+ 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 (long double) ?
+#if defined __i386__ && defined __FreeBSD__
+ L_(2400.0)
+#else
+ L_(24.0)
+#endif
+ : L_(24.0));
+
+ 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 */
+ DOUBLE z = - x - y;
+ /* Approximately x + y + z = 0. */
+ DOUBLE err = EXP (x) * EXP (y) * EXP (z) - L_(1.0);
+ ASSERT (err > - err_bound / TWO_MANT_DIG
+ && err < err_bound / TWO_MANT_DIG);
+ }
+ }
+}
+
+volatile DOUBLE x;
+DOUBLE y;