109 lines
4.2 KiB
C
109 lines
4.2 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 Andy Novocin
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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 "fmpz_poly.h"
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#include "fmpz_mod_poly.h"
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/*
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Macro for the lift G := [{(f - gh)/p} * b mod g] p + g.
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Assumes that {C, lenF} contains the inner part {f - gh}/p mod p1.
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Requires temporary space M, D, E. We really only need
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lenM = max(lenG, lenH)
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lenE = max(lenG + lenB - 2, lenH + lenA - 2)
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lenD = max(lenE, lenF)
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Only supports aliasing between G and g.
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*/
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#define lift(G, g, lenG, b, lenB) \
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do { \
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_fmpz_vec_scalar_mod_fmpz(M, g, lenG, p1); \
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_fmpz_mod_poly_rem(D, C, lenF, M, lenG, one, p1); \
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_fmpz_mod_poly_mul(E, D, lenG - 1, b, lenB, p1); \
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if (lenB > 1) \
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{ \
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_fmpz_mod_poly_rem(D, E, lenG + lenB - 2, M, lenG, one, p1); \
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_fmpz_vec_scalar_mul_fmpz(M, D, lenG - 1, p); \
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} \
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else \
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{ \
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_fmpz_vec_scalar_mul_fmpz(M, E, lenG - 1, p); \
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} \
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_fmpz_vec_add(G, g, M, lenG - 1); \
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fmpz_one(G + lenG - 1); \
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} while (0)
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void _fmpz_poly_hensel_lift_without_inverse(fmpz *G, fmpz *H,
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const fmpz *f, slong lenF,
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const fmpz *g, slong lenG, const fmpz *h, slong lenH,
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const fmpz *a, slong lenA, const fmpz *b, slong lenB,
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const fmpz_t p, const fmpz_t p1)
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{
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const fmpz one[1] = {1l};
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const slong lenM = FLINT_MAX(lenG, lenH);
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const slong lenE = FLINT_MAX(lenG + lenB - 2, lenH + lenA - 2);
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const slong lenD = FLINT_MAX(lenE, lenF);
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fmpz *C, *D, *E, *M;
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C = _fmpz_vec_init(lenF + lenD + lenE + lenM);
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D = C + lenF;
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E = D + lenD;
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M = E + lenE;
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if (lenG >= lenH)
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_fmpz_poly_mul(C, g,lenG, h, lenH);
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else
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_fmpz_poly_mul(C, h, lenH, g, lenG);
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_fmpz_vec_sub(C, f, C, lenF);
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_fmpz_vec_scalar_divexact_fmpz(D, C, lenF, p);
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_fmpz_vec_scalar_mod_fmpz(C, D, lenF, p1);
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lift(G, g, lenG, b, lenB);
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lift(H, h, lenH, a, lenA);
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_fmpz_vec_clear(C, lenF + lenD + lenE + lenM);
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}
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void fmpz_poly_hensel_lift_without_inverse(fmpz_poly_t Gout, fmpz_poly_t Hout,
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const fmpz_poly_t f, const fmpz_poly_t g, const fmpz_poly_t h,
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const fmpz_poly_t a, const fmpz_poly_t b,
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const fmpz_t p, const fmpz_t p1)
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{
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fmpz_poly_fit_length(Gout, g->length);
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fmpz_poly_fit_length(Hout, h->length);
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_fmpz_poly_set_length(Gout, g->length);
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_fmpz_poly_set_length(Hout, h->length);
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_fmpz_poly_hensel_lift_without_inverse(Gout->coeffs, Hout->coeffs,
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f->coeffs, f->length, g->coeffs, g->length, h->coeffs, h->length,
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a->coeffs, a->length, b->coeffs, b->length, p, p1);
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}
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