126 lines
3.1 KiB
C
126 lines
3.1 KiB
C
/*=============================================================================
|
|
|
|
This file is part of FLINT.
|
|
|
|
FLINT is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2 of the License, or
|
|
(at your option) any later version.
|
|
|
|
FLINT is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with FLINT; if not, write to the Free Software
|
|
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
|
|
|
|
=============================================================================*/
|
|
/******************************************************************************
|
|
|
|
Copyright (C) 2008, 2009 William Hart
|
|
Copyright (C) 2010 Sebastian Pancratz
|
|
|
|
******************************************************************************/
|
|
|
|
#include <stdlib.h>
|
|
#include <gmp.h>
|
|
#include "flint.h"
|
|
#include "fmpz.h"
|
|
#include "fmpz_vec.h"
|
|
#include "fmpz_poly.h"
|
|
|
|
void
|
|
_fmpz_poly_div_basecase(fmpz * Q, fmpz * R, const fmpz * A, slong lenA,
|
|
const fmpz * B, slong lenB)
|
|
{
|
|
const fmpz * leadB = B + lenB - 1;
|
|
slong B1, iQ = lenA - lenB;
|
|
slong alloc;
|
|
|
|
while (lenA >= lenB && fmpz_cmpabs(A + lenA - 1, leadB) < 0)
|
|
{
|
|
fmpz_zero(Q + iQ);
|
|
iQ--;
|
|
lenA--;
|
|
}
|
|
|
|
if (lenA < lenB)
|
|
return;
|
|
|
|
alloc = (R == NULL) ? lenA : 0;
|
|
if (alloc)
|
|
R = _fmpz_vec_init(alloc);
|
|
if (R != A)
|
|
_fmpz_vec_set(R + lenB - 1, A + lenB - 1, lenA - lenB + 1);
|
|
|
|
B1 = lenB - 1;
|
|
|
|
while (lenA >= lenB)
|
|
{
|
|
if (fmpz_cmpabs(R + lenA - 1, leadB) < 0)
|
|
fmpz_zero(Q + iQ);
|
|
else
|
|
{
|
|
fmpz_fdiv_q(Q + iQ, R + lenA - 1, leadB);
|
|
_fmpz_vec_scalar_submul_fmpz(R + lenA - B1 - 1, B, B1, Q + iQ);
|
|
}
|
|
|
|
if (B1 >= lenA - lenB + 1)
|
|
{
|
|
B++;
|
|
B1--;
|
|
}
|
|
|
|
lenA--;
|
|
iQ--;
|
|
}
|
|
|
|
if (alloc)
|
|
_fmpz_vec_clear(R, alloc);
|
|
}
|
|
|
|
void
|
|
fmpz_poly_div_basecase(fmpz_poly_t Q,
|
|
const fmpz_poly_t A, const fmpz_poly_t B)
|
|
{
|
|
slong lenq;
|
|
fmpz *q;
|
|
|
|
if (B->length == 0)
|
|
{
|
|
flint_printf("Exception (fmpz_poly_div_basecase). Division by zero.\n");
|
|
abort();
|
|
}
|
|
if (A->length < B->length)
|
|
{
|
|
fmpz_poly_zero(Q);
|
|
return;
|
|
}
|
|
|
|
lenq = A->length - B->length + 1;
|
|
if ((Q == A) || (Q == B))
|
|
q = _fmpz_vec_init(lenq);
|
|
else
|
|
{
|
|
fmpz_poly_fit_length(Q, lenq);
|
|
q = Q->coeffs;
|
|
}
|
|
|
|
_fmpz_poly_div_basecase(q, NULL, A->coeffs, A->length,
|
|
B->coeffs, B->length);
|
|
|
|
if ((Q == A) || (Q == B))
|
|
{
|
|
_fmpz_vec_clear(Q->coeffs, Q->alloc);
|
|
Q->coeffs = q;
|
|
Q->alloc = lenq;
|
|
Q->length = lenq;
|
|
}
|
|
else
|
|
_fmpz_poly_set_length(Q, lenq);
|
|
|
|
_fmpz_poly_normalise(Q);
|
|
}
|