139 lines
4.0 KiB
C
139 lines
4.0 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_lcm(fmpz *L, fmpz_t denL,
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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(L);
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fmpz_one(denL);
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}
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else
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{
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fmpz *copyA, *copyB;
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fmpz_t s, t;
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slong lenL;
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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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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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copyA = (fmpz *) A;
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copyB = (fmpz *) B;
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}
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else
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{
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copyA = (fmpz *) A;
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copyB = _fmpz_vec_init(lenB);
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_fmpz_vec_scalar_divexact_fmpz(copyB, 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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copyA = _fmpz_vec_init(lenA);
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copyB = (fmpz *) B;
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_fmpz_vec_scalar_divexact_fmpz(copyA, A, lenA, s);
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}
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else
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{
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copyA = _fmpz_vec_init(lenA + lenB);
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copyB = copyA + lenA;
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_fmpz_vec_scalar_divexact_fmpz(copyA, A, lenA, s);
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_fmpz_vec_scalar_divexact_fmpz(copyB, B, lenB, t);
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}
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}
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_fmpz_poly_lcm(L, copyA, lenA, copyB, lenB);
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for (lenL = lenA + lenB - 2; !L[lenL]; lenL--) ;
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lenL++;
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fmpz_set(denL, L + (lenL - 1));
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if (A != copyA)
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_fmpz_vec_clear(copyA, lenA + (B != copyB) * lenB);
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else if (B != copyB)
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_fmpz_vec_clear(copyB, 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_lcm(fmpq_poly_t L, const fmpq_poly_t A, const fmpq_poly_t B)
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{
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slong lenA = A->length, lenB = B->length, lenL = lenA + lenB - 1;
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if (lenA == 0 || lenB == 0)
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{
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fmpq_poly_zero(L);
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return;
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}
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if (L == A || L == B)
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{
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fmpq_poly_t t;
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fmpq_poly_init2(t, lenL);
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if (lenA >= lenB)
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_fmpq_poly_lcm(t->coeffs, t->den, A->coeffs, A->length,
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B->coeffs, B->length);
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else
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_fmpq_poly_lcm(t->coeffs, t->den, B->coeffs, B->length,
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A->coeffs, A->length);
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fmpq_poly_swap(t, L);
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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(L, lenL);
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if (lenA >= lenB)
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_fmpq_poly_lcm(L->coeffs, L->den, A->coeffs, A->length,
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B->coeffs, B->length);
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else
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_fmpq_poly_lcm(L->coeffs, L->den, B->coeffs, B->length,
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A->coeffs, A->length);
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}
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_fmpq_poly_set_length(L, lenL);
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_fmpq_poly_normalise(L);
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}
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