1  /* Euclidean distance function.  Double/Binary64 i386 version.
       2     Copyright (C) 2021-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <math.h>
      20  #include <math_private.h>
      21  #include <math-narrow-eval.h>
      22  #include <math-underflow.h>
      23  #include <math-svid-compat.h>
      24  #include <libm-alias-finite.h>
      25  #include <libm-alias-double.h>
      26  #include <errno.h>
      27  
      28  /* The i386 allows to use the default excess of precision to optimize the
      29     hypot implementation, since internal multiplication and sqrt is carried
      30     with 80-bit FP type.  */
      31  double
      32  __hypot (double x, double y)
      33  {
      34    if (!isfinite (x) || !isfinite (y))
      35      {
      36        if ((isinf (x) || isinf (y))
      37  	  && !issignaling (x) && !issignaling (y))
      38  	return INFINITY;
      39        return x + y;
      40      }
      41  
      42    long double lx = x;
      43    long double ly = y;
      44    double r = math_narrow_eval ((double) sqrtl (lx * lx + ly * ly));
      45    math_check_force_underflow_nonneg (r);
      46    if (isinf (r))
      47      __set_errno (ERANGE);
      48    return r;
      49  }
      50  strong_alias (__hypot, __ieee754_hypot)
      51  #if LIBM_SVID_COMPAT
      52  versioned_symbol (libm, __hypot, hypot, GLIBC_2_35);
      53  libm_alias_finite (__ieee754_hypot, __hypot)
      54  libm_alias_double_other (__hypot, hypot)
      55  #else
      56  libm_alias_double (__hypot, hypot)
      57  #endif