hypot* tests: More tests.

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

diff --git a/tests/test-hypot.h b/tests/test-hypot.h
new file mode 100644 (file)
index 0000000..cdc555b
--- /dev/null
+++ b/tests/test-hypot.h
@@ -0,0 +1,72 @@
+/* Test of hypot*() 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));
+
+  {
+    volatile DOUBLE x;
+    volatile DOUBLE y;
+    DOUBLE z;
+
+    /* Overflow.  */
+    x = MAX;
+    y = MAX * L_(0.5);
+    z = HYPOT (x, y);
+    ASSERT (z == HUGEVAL);
+
+    /* No underflow.  */
+    x = MIN;
+    y = L_(0.0);
+    z = HYPOT (x, y);
+    ASSERT (z == MIN);
+
+    /* No underflow.  */
+    x = MIN * L_(2.0);
+    y = MIN * L_(3.0);
+    z = HYPOT (x, y);
+    ASSERT (z >= MIN * L_(2.0) && z <= MIN * L_(4.0));
+  }
+
+  /* Randomized tests.  */
+  for (i = 0; i < SIZEOF (RANDOM) / 5; i++)
+    for (j = 0; j < SIZEOF (RANDOM) / 5;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 */
+        DOUBLE z = HYPOT (x, y);
+        DOUBLE err = z * z - (x * x + y * y);
+        ASSERT (z >= L_(0.0));
+        ASSERT (err >= - L_(4.0) * L_(16.0) * L_(16.0) / TWO_MANT_DIG
+                && err <= L_(4.0) * L_(16.0) * L_(16.0) / TWO_MANT_DIG);
+      }
+}
+
+volatile DOUBLE x;
+volatile DOUBLE y;
+DOUBLE z;