126 lines
3.1 KiB
C
126 lines
3.1 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) 2008, 2009 William Hart
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Copyright (C) 2010 Sebastian Pancratz
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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 "fmpz_vec.h"
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#include "fmpz_poly.h"
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void
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_fmpz_poly_div_basecase(fmpz * Q, fmpz * R, const fmpz * A, slong lenA,
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const fmpz * B, slong lenB)
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{
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const fmpz * leadB = B + lenB - 1;
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slong B1, iQ = lenA - lenB;
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slong alloc;
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while (lenA >= lenB && fmpz_cmpabs(A + lenA - 1, leadB) < 0)
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{
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fmpz_zero(Q + iQ);
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iQ--;
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lenA--;
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}
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if (lenA < lenB)
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return;
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alloc = (R == NULL) ? lenA : 0;
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if (alloc)
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R = _fmpz_vec_init(alloc);
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if (R != A)
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_fmpz_vec_set(R + lenB - 1, A + lenB - 1, lenA - lenB + 1);
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B1 = lenB - 1;
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while (lenA >= lenB)
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{
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if (fmpz_cmpabs(R + lenA - 1, leadB) < 0)
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fmpz_zero(Q + iQ);
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else
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{
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fmpz_fdiv_q(Q + iQ, R + lenA - 1, leadB);
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_fmpz_vec_scalar_submul_fmpz(R + lenA - B1 - 1, B, B1, Q + iQ);
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}
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if (B1 >= lenA - lenB + 1)
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{
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B++;
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B1--;
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}
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lenA--;
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iQ--;
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}
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if (alloc)
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_fmpz_vec_clear(R, alloc);
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}
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void
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fmpz_poly_div_basecase(fmpz_poly_t Q,
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const fmpz_poly_t A, const fmpz_poly_t B)
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{
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slong lenq;
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fmpz *q;
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if (B->length == 0)
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{
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flint_printf("Exception (fmpz_poly_div_basecase). Division by zero.\n");
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abort();
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}
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if (A->length < B->length)
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{
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fmpz_poly_zero(Q);
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return;
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}
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lenq = A->length - B->length + 1;
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if ((Q == A) || (Q == B))
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q = _fmpz_vec_init(lenq);
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else
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{
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fmpz_poly_fit_length(Q, lenq);
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q = Q->coeffs;
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}
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_fmpz_poly_div_basecase(q, NULL, A->coeffs, A->length,
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B->coeffs, B->length);
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if ((Q == A) || (Q == B))
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{
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_fmpz_vec_clear(Q->coeffs, Q->alloc);
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Q->coeffs = q;
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Q->alloc = lenq;
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Q->length = lenq;
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}
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else
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_fmpz_poly_set_length(Q, lenq);
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_fmpz_poly_normalise(Q);
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}
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