100 lines
2.9 KiB
C
100 lines
2.9 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) 2011 Sebastian Pancratz
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Copyright (C) 2010 William Hart
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******************************************************************************/
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#include <stdlib.h>
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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 "fmpq.h"
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#include "fmpz_vec.h"
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#include "fmpq_poly.h"
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void fmpq_poly_set_coeff_fmpq(fmpq_poly_t poly, slong n, const fmpq_t x)
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{
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slong len = poly->length;
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const int replace = (n < len && !fmpz_is_zero(poly->coeffs + n));
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if (!replace && fmpq_is_zero(x))
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return;
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if (n + 1 > len)
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{
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fmpq_poly_fit_length(poly, n + 1);
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_fmpq_poly_set_length(poly, n + 1);
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flint_mpn_zero((mp_ptr) poly->coeffs + len, (n + 1) - len);
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len = n + 1;
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}
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if (replace)
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{
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fmpz_t c;
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fmpz_init(c);
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fmpz_zero(poly->coeffs + n);
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_fmpz_poly_content(c, poly->coeffs, len);
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_fmpz_vec_scalar_mul_fmpz(poly->coeffs, poly->coeffs, len, fmpq_denref(x));
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fmpz_mul(c, c, fmpq_denref(x));
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fmpz_mul(poly->coeffs + n, fmpq_numref(x), poly->den);
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fmpz_gcd(c, c, poly->coeffs + n);
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fmpz_mul(poly->den, poly->den, fmpq_denref(x));
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if (!fmpz_is_one(c))
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fmpz_gcd(c, c, poly->den);
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if (!fmpz_is_one(c))
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{
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_fmpz_vec_scalar_divexact_fmpz(poly->coeffs, poly->coeffs, len, c);
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fmpz_divexact(poly->den, poly->den, c);
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}
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_fmpq_poly_normalise(poly);
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fmpz_clear(c);
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}
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else
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{
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fmpz_t d, t;
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fmpz_init(d);
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fmpz_init(t);
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fmpz_gcd(d, poly->den, fmpq_denref(x));
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fmpz_divexact(t, fmpq_denref(x), d);
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_fmpz_vec_scalar_mul_fmpz(poly->coeffs, poly->coeffs, len, t);
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fmpz_set(poly->coeffs + n, fmpq_numref(x));
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fmpz_mul(poly->coeffs + n, poly->coeffs + n, poly->den);
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fmpz_divexact(poly->coeffs + n, poly->coeffs + n, d);
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fmpz_mul(poly->den, poly->den, t);
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fmpz_clear(d);
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fmpz_clear(t);
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}
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}
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