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diff --git a/REORG.TODO/sysdeps/ieee754/dbl-64/x2y2m1f.c b/REORG.TODO/sysdeps/ieee754/dbl-64/x2y2m1f.c
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+++ b/REORG.TODO/sysdeps/ieee754/dbl-64/x2y2m1f.c
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+/* Compute x^2 + y^2 - 1, without large cancellation error.
+ Copyright (C) 2012-2017 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 X^2 + Y^2 >=
+ 0.5. */
+
+float
+__x2y2m1f (float x, float y)
+{
+ double dx = x, dy = y;
+ return (float) ((dx - 1) * (dx + 1) + dy * dy);
+}