tests/test-hypot.h

   1 /* Test of hypot*() function family.
   2    Copyright (C) 2012-2024 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 static void
  18 test_function (void)
  19 {
  20   int i;
  21   int j;
  22   const DOUBLE TWO_MANT_DIG =
  23     /* Assume MANT_DIG <= 5 * 31.
  24        Use the identity
  25          n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5).  */
  26     (DOUBLE) (1U << ((MANT_DIG - 1) / 5))
  27     * (DOUBLE) (1U << ((MANT_DIG - 1 + 1) / 5))
  28     * (DOUBLE) (1U << ((MANT_DIG - 1 + 2) / 5))
  29     * (DOUBLE) (1U << ((MANT_DIG - 1 + 3) / 5))
  30     * (DOUBLE) (1U << ((MANT_DIG - 1 + 4) / 5));
  31
  32   {
  33     volatile DOUBLE x;
  34     volatile DOUBLE y;
  35     volatile DOUBLE z;
  36
  37     /* Overflow.  */
  38     x = MAX;
  39     y = MAX * L_(0.5);
  40     z = HYPOT (x, y);
  41     ASSERT (z == HUGEVAL);
  42
  43     /* No underflow.  */
  44     x = MIN;
  45     y = L_(0.0);
  46     z = HYPOT (x, y);
  47     ASSERT (z == MIN);
  48
  49     /* No underflow.  */
  50     x = MIN * L_(2.0);
  51     y = MIN * L_(3.0);
  52     z = HYPOT (x, y);
  53     ASSERT (z >= MIN * L_(2.0) && z <= MIN * L_(4.0));
  54   }
  55
  56   /* Randomized tests.  */
  57   for (i = 0; i < SIZEOF (RANDOM) / 5; i++)
  58     for (j = 0; j < SIZEOF (RANDOM) / 5;j++)
  59       {
  60         DOUBLE x = L_(16.0) * RANDOM[i]; /* 0.0 <= x <= 16.0 */
  61         DOUBLE y = L_(16.0) * RANDOM[j]; /* 0.0 <= y <= 16.0 */
  62         DOUBLE z = HYPOT (x, y);
  63         DOUBLE err = z * z - (x * x + y * y);
  64         ASSERT (z >= L_(0.0));
  65         ASSERT (err >= - L_(4.0) * L_(16.0) * L_(16.0) / TWO_MANT_DIG
  66                 && err <= L_(4.0) * L_(16.0) * L_(16.0) / TWO_MANT_DIG);
  67       }
  68 }
  69
  70 volatile DOUBLE x;
  71 volatile DOUBLE y;
  72 DOUBLE z;