1/* Compute x^2 + y^2 - 1, without large cancellation error.
2 Copyright (C) 2012-2018 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 <http://www.gnu.org/licenses/>. */
18
19#include <math.h>
20#include <math_private.h>
21#include <float.h>
22
23#if FLT_EVAL_METHOD == 0
24
25# include <sysdeps/ieee754/dbl-64/x2y2m1.c>
26
27#else
28
29/* Return X^2 + Y^2 - 1, computed without large cancellation error.
30 It is given that 1 > X >= Y >= epsilon / 2, and that X^2 + Y^2 >=
31 0.5. */
32
33double
34__x2y2m1 (double x, double y)
35{
36 return (double) __x2y2m1l (x, y);
37}
38
39#endif
40