maint/gnulib/lib/hypotl.c

/* */
This source file includes following definitions.
hypotl
hypotl
   1 /* Hypotenuse of a right-angled triangle.
   2    Copyright (C) 2012-2021 Free Software Foundation, Inc.
   3 
   4    This file is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation; either version 3 of the
   7    License, or (at your option) any later version.
   8 
   9    This file 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 Lesser General Public License for more details.
  13 
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16 
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2012.  */
  18 
  19 #include <config.h>
  20 
  21 /* Specification.  */
  22 #include <math.h>
  23 
  24 #if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
  25 
  26 long double
  27 hypotl (long double x, long double y)
     /*  */
  28 {
  29   return hypot (x, y);
  30 }
  31 
  32 #else
  33 
  34 long double
  35 hypotl (long double x, long double y)
     /*  */
  36 {
  37   if (isfinite (x) && isfinite (y))
  38     {
  39       /* Determine absolute values.  */
  40       x = fabsl (x);
  41       y = fabsl (y);
  42 
  43       {
  44         /* Find the bigger and the smaller one.  */
  45         long double a;
  46         long double b;
  47 
  48         if (x >= y)
  49           {
  50             a = x;
  51             b = y;
  52           }
  53         else
  54           {
  55             a = y;
  56             b = x;
  57           }
  58         /* Now 0 <= b <= a.  */
  59 
  60         {
  61           int e;
  62           long double an;
  63           long double bn;
  64 
  65           /* Write a = an * 2^e, b = bn * 2^e with 0 <= bn <= an < 1.  */
  66           an = frexpl (a, &e);
  67           bn = ldexpl (b, - e);
  68 
  69           {
  70             long double cn;
  71 
  72             /* Through the normalization, no unneeded overflow or underflow
  73                will occur here.  */
  74             cn = sqrtl (an * an + bn * bn);
  75             return ldexpl (cn, e);
  76           }
  77         }
  78       }
  79     }
  80   else
  81     {
  82       if (isinf (x) || isinf (y))
  83         /* x or y is infinite.  Return +Infinity.  */
  84         return HUGE_VALL;
  85       else
  86         /* x or y is NaN.  Return NaN.  */
  87         return x + y;
  88     }
  89 }
  90 
  91 #endif
/* */
root/maint/gnulib/lib/hypotl.c

DEFINITIONS
