147 lines
4.1 KiB
C
147 lines
4.1 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 <stdlib.h>
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#include "flint.h"
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#include "fmpz.h"
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#include "fmpz_vec.h"
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#include "fmpz_poly.h"
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#include "fmpq_poly.h"
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void _fmpq_poly_gcd(fmpz *G, fmpz_t denG,
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const fmpz *A, slong lenA, const fmpz *B, slong lenB)
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{
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if (lenA == 1) /* lenA == lenB == 1 */
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{
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fmpz_one(G);
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fmpz_one(denG);
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}
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else
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{
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fmpz *primA, *primB;
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fmpz_t s, t;
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slong lenG;
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fmpz_init(s);
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fmpz_init(t);
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_fmpz_vec_content(s, A, lenA);
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_fmpz_vec_content(t, B, lenB);
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/* Set primA, primB to the primitive multiples of A, B */
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if (fmpz_is_one(s))
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{
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if (fmpz_is_one(t))
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{
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primA = (fmpz *) A;
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primB = (fmpz *) B;
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}
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else
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{
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primA = (fmpz *) A;
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primB = _fmpz_vec_init(lenB);
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_fmpz_vec_scalar_divexact_fmpz(primB, B, lenB, t);
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}
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}
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else
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{
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if (fmpz_is_one(s))
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{
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primA = _fmpz_vec_init(lenA);
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primB = (fmpz *) B;
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_fmpz_vec_scalar_divexact_fmpz(primA, A, lenA, s);
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}
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else
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{
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primA = _fmpz_vec_init(lenA + lenB);
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primB = primA + lenA;
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_fmpz_vec_scalar_divexact_fmpz(primA, A, lenA, s);
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_fmpz_vec_scalar_divexact_fmpz(primB, B, lenB, t);
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}
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}
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_fmpz_poly_gcd(G, primA, lenA, primB, lenB);
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for (lenG = lenB - 1; !G[lenG]; lenG--) ;
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lenG++;
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fmpz_set(denG, G + (lenG - 1));
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if (A != primA)
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_fmpz_vec_clear(primA, lenA + (B != primB) * lenB);
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else if (B != primB)
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_fmpz_vec_clear(primB, lenB);
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fmpz_clear(s);
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fmpz_clear(t);
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}
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}
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void fmpq_poly_gcd(fmpq_poly_t G, const fmpq_poly_t A, const fmpq_poly_t B)
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{
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if (A->length < B->length)
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{
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fmpq_poly_gcd(G, B, A);
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}
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else
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{
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slong lenA = A->length, lenB = B->length;
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if (lenA == 0) /* lenA = lenB = 0 */
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{
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fmpq_poly_zero(G);
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}
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else if (lenB == 0) /* lenA > lenB = 0 */
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{
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fmpq_poly_make_monic(G, A);
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}
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else /* lenA >= lenB >= 1 */
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{
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if (G == A || G == B)
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{
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fmpq_poly_t t;
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fmpq_poly_init2(t, lenB);
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_fmpq_poly_gcd(t->coeffs, t->den, A->coeffs, A->length,
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B->coeffs, B->length);
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fmpq_poly_swap(t, G);
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fmpq_poly_clear(t);
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}
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else
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{
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fmpq_poly_fit_length(G, lenB);
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_fmpq_poly_gcd(G->coeffs, G->den, A->coeffs, A->length,
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B->coeffs, B->length);
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}
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_fmpq_poly_set_length(G, lenB);
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_fmpq_poly_normalise(G);
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}
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}
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}
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