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/* __gmpfr_isqrt && __gmpfr_cuberoot -- Interger square root and cubic root
Copyright 2004 Free Software Foundation, Inc.
This file is part of the MPFR Library.
The MPFR 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 MPFR 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 MPFR Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include "mpfr-impl.h"
/* returns floor(sqrt(n)) */
unsigned long
__gmpfr_isqrt (unsigned long n)
{
unsigned long s;
s = 1;
do {
s = (s + n / s) / 2;
} while (!(s*s <= n && n <= s*(s+2)));
return s;
}
/* returns floor(n^(1/3)) */
unsigned long
__gmpfr_cuberoot (unsigned long n)
{
double s, is;
s = 1.0;
do {
s = (2*s*s*s + (double) n) / (3*s*s);
is = (double) ((int) s);
} while (!(is*is*is <= (double) n && (double) n < (is+1)*(is+1)*(is+1)));
return (unsigned long) is;
}
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