exp* tests: More tests.

[gnulib.git] / tests / test-exp.h

diff --git a/tests/test-exp.h b/tests/test-exp.h
new file mode 100644 (file)
index 0000000..c2609b7
--- /dev/null
+++ b/tests/test-exp.h
@@ -0,0 +1,88 @@
+/* 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;