106 lines
3.2 KiB
C
106 lines
3.2 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) 2010 Sebastian Pancratz
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Copyright (C) 2010 William Hart
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Copyright (C) 2012 Lina Kulakova
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******************************************************************************/
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#include <gmp.h>
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#include "flint.h"
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#include "fmpz_vec.h"
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#include "fmpz_mod_poly.h"
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void
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_fmpz_mod_poly_pow_trunc(fmpz * res, const fmpz * poly,
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ulong e, slong trunc, const fmpz_t p)
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{
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_fmpz_mod_poly_pow_trunc_binexp(res, poly, e, trunc, p);
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}
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void
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fmpz_mod_poly_pow_trunc(fmpz_mod_poly_t res,
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const fmpz_mod_poly_t poly, ulong e, slong trunc)
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{
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const slong len = poly->length;
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fmpz * q;
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int qcopy = 0;
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if (len < 2 || e < UWORD(3) || trunc == 0)
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{
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if (len == 0 || trunc == 0)
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fmpz_mod_poly_zero(res);
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else if (len == 1)
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{
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fmpz_mod_poly_fit_length(res, 1);
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fmpz_powm_ui(res->coeffs, poly->coeffs, e, &res->p);
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_fmpz_mod_poly_set_length(res, 1);
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_fmpz_mod_poly_normalise(res);
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}
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else if (e == UWORD(0))
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{
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fmpz_mod_poly_set_coeff_ui(res, 0, UWORD(1));
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_fmpz_mod_poly_set_length(res, 1);
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_fmpz_mod_poly_normalise(res);
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}
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else if (e == UWORD(1))
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{
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fmpz_mod_poly_set(res, poly);
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fmpz_mod_poly_truncate(res, trunc);
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}
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else /* e == UWORD(2) */
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fmpz_mod_poly_mullow(res, poly, poly, trunc);
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return;
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}
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if (poly->length < trunc)
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{
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q = _fmpz_vec_init(trunc);
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_fmpz_vec_set(q, poly->coeffs, poly->length);
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_fmpz_vec_zero(q + poly->length, trunc - poly->length);
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qcopy = 1;
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} else
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q = poly->coeffs;
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if (res != poly || qcopy)
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{
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fmpz_mod_poly_fit_length(res, trunc);
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_fmpz_mod_poly_pow_trunc(res->coeffs, q, e, trunc, &poly->p);
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}
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else
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{
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fmpz_mod_poly_t t;
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fmpz_mod_poly_init2(t, &poly->p, trunc);
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_fmpz_mod_poly_pow_trunc(t->coeffs, q, e, trunc, &poly->p);
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fmpz_mod_poly_swap(res, t);
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fmpz_mod_poly_clear(t);
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}
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if (qcopy)
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_fmpz_vec_clear(q, trunc);
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_fmpz_mod_poly_set_length(res, trunc);
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_fmpz_mod_poly_normalise(res);
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}
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