145 lines
3.6 KiB
C
145 lines
3.6 KiB
C
/*=============================================================================
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This file is part of FLINT.
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FLINT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FLINT 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 General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FLINT; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2011 Sebastian Pancratz
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******************************************************************************/
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#include <gmp.h>
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#include "flint.h"
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#include "fmpz.h"
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#include "ulong_extras.h"
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slong _fmpz_remove(fmpz_t x, const fmpz_t f, double finv)
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{
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fmpz y = *x;
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fmpz q = *f;
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if (!COEFF_IS_MPZ(y)) /* x is small */
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{
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if (!COEFF_IS_MPZ(q)) /* f is small */
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{
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if (y > 0)
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{
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return n_remove2_precomp((mp_limb_t *) x, q, finv);
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}
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else
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{
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ulong z = - (ulong) y;
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slong e = n_remove2_precomp(&z, q, finv);
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if (e > 0)
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{
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*x = - (slong) z;
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}
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return e;
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}
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}
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else /* f is large */
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{
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return 0;
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}
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}
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else /* x is large */
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{
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__mpz_struct *z = COEFF_TO_PTR(y);
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if (!COEFF_IS_MPZ(q)) /* f is small */
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{
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if (!flint_mpz_divisible_ui_p(z, q))
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{
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return 0;
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}
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else
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{
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flint_mpz_divexact_ui(z, z, q);
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if (!flint_mpz_divisible_ui_p(z, q))
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{
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_fmpz_demote_val(x);
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return 1;
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}
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else
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{
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mpz_t r;
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slong e;
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flint_mpz_divexact_ui(z, z, q);
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flint_mpz_init_set_ui(r, q);
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e = 2 + mpz_remove(z, z, r);
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mpz_clear(r);
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_fmpz_demote_val(x);
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return e;
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}
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}
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}
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else /* f is large */
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{
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__mpz_struct *r = COEFF_TO_PTR(q);
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if (!mpz_divisible_p(z, r))
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{
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return 0;
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}
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else
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{
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slong e;
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mpz_divexact(z, z, r);
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e = 1 + mpz_remove(z, z, r);
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_fmpz_demote_val(x);
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return e;
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}
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}
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}
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}
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slong fmpz_remove(fmpz_t rop, const fmpz_t op, const fmpz_t f)
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{
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double finv;
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if ((fmpz_sgn(f) <= 0) || fmpz_is_one(f))
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{
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flint_printf("Exception (fmpz_remove). factor f <= 1.\n");
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abort();
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}
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if (rop == f)
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{
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slong ans;
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fmpz_t t;
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fmpz_init(t);
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ans = fmpz_remove(t, op, f);
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fmpz_swap(rop, t);
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fmpz_clear(t);
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return ans;
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}
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finv = (!COEFF_IS_MPZ((*f))) ? n_precompute_inverse(*f) : 0;
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fmpz_set(rop, op);
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return _fmpz_remove(rop, f, finv);
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}
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