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/* Emulation for sqrtl.
Contributed by Paolo Bonzini
Copyright 2002-2003, 2007, 2009-2015 Free Software Foundation, Inc.
This file is part of gnulib.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include <math.h>
#if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
long double
sqrtl (long double x)
{
return sqrt (x);
}
#else
# include <float.h>
/* A simple Newton-Raphson method. */
long double
sqrtl (long double x)
{
long double delta, y;
int exponent;
/* Check for NaN */
if (isnanl (x))
return x;
/* Check for negative numbers */
if (x < 0.0L)
return (long double) sqrt (-1);
/* Check for zero and infinites */
if (x + x == x)
return x;
frexpl (x, &exponent);
y = ldexpl (x, -exponent / 2);
do
{
delta = y;
y = (y + x / y) * 0.5L;
delta -= y;
}
while (delta != 0.0L);
return y;
}
#endif
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