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/* mpz_root(root, u, nth) -- Set ROOT to floor(U^(1/nth)).
Return an indication if the result is exact.
Copyright 1999-2003, 2005, 2012 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP 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 3 of the License, or (at your
option) any later version.
The GNU MP 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 MP Library. If not, see https://www.gnu.org/licenses/. */
#include <stdio.h> /* for NULL */
#include "gmp.h"
#include "gmp-impl.h"
int
mpz_root (mpz_ptr root, mpz_srcptr u, unsigned long int nth)
{
mp_ptr rootp, up;
mp_size_t us, un, rootn, remn;
TMP_DECL;
us = SIZ(u);
/* even roots of negatives provoke an exception */
if (UNLIKELY (us < 0 && (nth & 1) == 0))
SQRT_OF_NEGATIVE;
/* root extraction interpreted as c^(1/nth) means a zeroth root should
provoke a divide by zero, do this even if c==0 */
if (UNLIKELY (nth == 0))
DIVIDE_BY_ZERO;
if (us == 0)
{
if (root != NULL)
SIZ(root) = 0;
return 1; /* exact result */
}
un = ABS (us);
rootn = (un - 1) / nth + 1;
TMP_MARK;
/* FIXME: Perhaps disallow root == NULL */
if (root != NULL && u != root)
rootp = MPZ_REALLOC (root, rootn);
else
rootp = TMP_ALLOC_LIMBS (rootn);
up = PTR(u);
if (nth == 1)
{
MPN_COPY (rootp, up, un);
remn = 0;
}
else
{
remn = mpn_rootrem (rootp, NULL, up, un, (mp_limb_t) nth);
}
if (root != NULL)
{
SIZ(root) = us >= 0 ? rootn : -rootn;
if (u == root)
MPN_COPY (up, rootp, rootn);
}
TMP_FREE;
return remn == 0;
}
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