115 lines
3.0 KiB
C
115 lines
3.0 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, 2010 Sebastian Pancratz
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Copyright (C) 2008, 2009 William Hart
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******************************************************************************/
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#include <stdlib.h>
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#include "fmpz_vec.h"
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#include "fmpz_mod_poly.h"
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void _fmpz_mod_poly_div_basecase(fmpz *Q, fmpz *R,
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const fmpz *A, slong lenA, const fmpz *B, slong lenB,
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const fmpz_t invB, const fmpz_t p)
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{
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const slong alloc = (R == NULL) ? lenA : 0;
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slong lenR = lenB - 1, iQ;
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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 + lenR, A + lenR, lenA - lenR);
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for (iQ = lenA - lenB; iQ >= 0; iQ--)
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{
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if (fmpz_is_zero(R + lenA - 1))
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{
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fmpz_zero(Q + iQ);
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}
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else
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{
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fmpz_mul(Q + iQ, R + lenA - 1, invB);
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fmpz_mod(Q + iQ, Q + iQ, p);
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_fmpz_vec_scalar_submul_fmpz(R + lenA - lenR - 1, B, lenR, Q + iQ);
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_fmpz_vec_scalar_mod_fmpz(R + lenA - lenR - 1, R + lenA - lenR - 1, lenR, p);
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}
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if (lenR - 1 >= iQ)
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{
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B++;
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lenR--;
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}
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lenA--;
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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 fmpz_mod_poly_div_basecase(fmpz_mod_poly_t Q,
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const fmpz_mod_poly_t A, const fmpz_mod_poly_t B)
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{
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const slong lenA = A->length, lenB = B->length, lenQ = lenA - lenB + 1;
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fmpz *q;
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fmpz_t invB;
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if (lenA < lenB)
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{
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fmpz_mod_poly_zero(Q);
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return;
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}
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fmpz_init(invB);
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fmpz_invmod(invB, B->coeffs + (lenB - 1), &(B->p));
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if (Q == A || Q == B)
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{
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q = _fmpz_vec_init(lenQ);
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}
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else
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{
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fmpz_mod_poly_fit_length(Q, lenQ);
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q = Q->coeffs;
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}
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_fmpz_mod_poly_div_basecase(q, NULL, A->coeffs, lenA,
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B->coeffs, lenB, invB, &(B->p));
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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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{
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_fmpz_mod_poly_set_length(Q, lenQ);
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}
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fmpz_clear(invB);
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}
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