| /* Compute x^2 + y^2 - 1, without large cancellation error. |
| Copyright (C) 2012-2014 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <math.h> |
| #include <math_private.h> |
| #include <float.h> |
| |
| /* Return X^2 + Y^2 - 1, computed without large cancellation error. |
| It is given that 1 > X >= Y >= epsilon / 2, and that either X >= |
| 0.75 or Y >= 0.5. */ |
| |
| float |
| __x2y2m1f (float x, float y) |
| { |
| double dx = x, dy = y; |
| return (float) ((dx - 1) * (dx + 1) + dy * dy); |
| } |
