84 lines
2.7 KiB
C
84 lines
2.7 KiB
C
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/*=============================================================================
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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) 2013 William Hart
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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 "fmpq_poly.h"
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fmpq_poly_struct *
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_fmpq_poly_powers_precompute(const fmpz * B, const fmpz_t denB, slong len)
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{
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slong i;
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fmpq_poly_struct * powers = flint_malloc(sizeof(fmpq_poly_struct)*(2*len - 1));
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fmpq_poly_t pow, p;
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fmpq_poly_init2(pow, len);
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fmpq_poly_one(pow);
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fmpq_poly_init2(p, len - 1);
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for (i = 0; i < 2*len - 1; i++)
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{
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fmpq_poly_init(powers + i);
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if (pow->length == len) /* reduce pow mod B */
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{
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fmpz_mul(fmpq_poly_denref(p), B + len - 1, fmpq_poly_denref(pow));
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_fmpz_vec_scalar_mul_fmpz(fmpq_poly_numref(p), B, len - 1,
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fmpq_poly_numref(pow) + len - 1);
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_fmpq_poly_set_length(p, len - 1);
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_fmpq_poly_normalise(p);
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fmpq_poly_canonicalise(p);
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fmpq_poly_sub(pow, pow, p);
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_fmpq_poly_set_length(pow, len - 1);
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_fmpq_poly_normalise(pow);
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fmpq_poly_canonicalise(pow);
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}
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fmpq_poly_set(powers + i, pow);
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fmpq_poly_shift_left(pow, pow, 1);
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}
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fmpq_poly_clear(pow);
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fmpq_poly_clear(p);
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return powers;
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}
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void fmpq_poly_powers_precompute(fmpq_poly_powers_precomp_t pinv,
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fmpq_poly_t poly)
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{
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if (poly->length == 0)
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{
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flint_printf("Exception (fmpz_poly_powers_precompute). Division by zero.\n");
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abort();
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}
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pinv->powers = _fmpq_poly_powers_precompute(fmpq_poly_numref(poly),
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fmpq_poly_denref(poly), poly->length);
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pinv->len = poly->length;
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}
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