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72 lines
1.5 KiB
C
72 lines
1.5 KiB
C
/* Emulation for sqrtl.
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Contributed by Paolo Bonzini
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Copyright 2002-2003, 2007, 2009-2022 Free Software Foundation, Inc.
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This file is part of gnulib.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 3 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#include <config.h>
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/* Specification. */
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#include <math.h>
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#if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
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long double
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sqrtl (long double x)
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{
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return sqrt (x);
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}
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#else
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# include <float.h>
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/* A simple Newton-Raphson method. */
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long double
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sqrtl (long double x)
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{
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long double delta, y;
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int exponent;
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/* Check for NaN */
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if (isnanl (x))
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return x;
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/* Check for negative numbers */
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if (x < 0.0L)
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return (long double) sqrt (-1);
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/* Check for zero and infinites */
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if (x + x == x)
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return x;
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frexpl (x, &exponent);
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y = ldexpl (x, -exponent / 2);
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do
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{
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delta = y;
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y = (y + x / y) * 0.5L;
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delta -= y;
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}
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while (delta != 0.0L);
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return y;
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}
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#endif
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