kc3-lang/gnulib/tests/test-sqrt.h

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• Hash : 32a72f45
  Author :
  Date : 2023-01-01T01:14:21
  

  maint: run 'make update-copyright'
  

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• tests/test-sqrt.h

• /* Test of sqrt*() function family.
     Copyright (C) 2012-2023 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 <https://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.  */
    for (i = 0; i < SIZEOF (RANDOM); i++)
      {
        DOUBLE x = L_(16.0) * RANDOM[i]; /* 0.0 <= x <= 16.0 */
        DOUBLE y = SQRT (x);
        DOUBLE err = y * y - x;
        ASSERT (y >= L_(0.0));
        ASSERT (err > - L_(16.0) / TWO_MANT_DIG
                && err < L_(16.0) / TWO_MANT_DIG);
      }
  
    for (i = 0; i < SIZEOF (RANDOM) / 4; i++)
      for (j = 0; j < SIZEOF (RANDOM) / 4; 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 */
          if (x > L_(0.0) && y > L_(0.0))
            {
              DOUBLE z = L_(1.0) / (x * y);
              /* Approximately  x * y * z = 1.  */
              DOUBLE p = SQRT (x) * SQRT (y) * SQRT (z);
              ASSERT (p > L_(1.0) - L_(4.0) / TWO_MANT_DIG
                      && p < L_(1.0) + L_(4.0) / TWO_MANT_DIG);
            }
        }
  }
  
  volatile DOUBLE x;
  DOUBLE y;
  

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