82 lines
2.0 KiB
C
82 lines
2.0 KiB
C
/* mpz_root(root, u, nth) -- Set ROOT to floor(U^(1/nth)).
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Return an indication if the result is exact.
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Copyright 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library 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 published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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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 the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include <stdio.h> /* for NULL */
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#include "gmp.h"
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#include "gmp-impl.h"
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int
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mpz_root (mpz_ptr root, mpz_srcptr u, unsigned long int nth)
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{
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mp_ptr rootp, up;
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mp_size_t us, un, rootn, remn;
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up = PTR(u);
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us = SIZ(u);
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/* even roots of negatives provoke an exception */
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if (us < 0 && (nth & 1) == 0)
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SQRT_OF_NEGATIVE;
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/* root extraction interpreted as c^(1/nth) means a zeroth root should
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provoke a divide by zero, do this even if c==0 */
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if (nth == 0)
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DIVIDE_BY_ZERO;
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if (us == 0)
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{
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if (root != NULL)
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SIZ(root) = 0;
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return 1; /* exact result */
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}
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un = ABS (us);
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rootn = (un - 1) / nth + 1;
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if (root != NULL)
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{
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rootp = MPZ_REALLOC (root, rootn);
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up = PTR(u);
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}
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else
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{
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rootp = __GMP_ALLOCATE_FUNC_LIMBS (rootn);
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}
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if (nth == 1)
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{
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MPN_COPY (rootp, up, un);
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remn = 0;
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}
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else
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{
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remn = mpn_rootrem (rootp, NULL, up, un, (mp_limb_t) nth);
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}
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if (root != NULL)
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SIZ(root) = us >= 0 ? rootn : -rootn;
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else
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__GMP_FREE_FUNC_LIMBS (rootp, rootn);
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return remn == 0;
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}
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