1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
|
/*=============================================================================
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) 2010 Sebastian Pancratz
******************************************************************************/
#include <gmp.h>
#include "flint.h"
#include "fmpz.h"
#include "fmpz_vec.h"
#include "fmpz_poly.h"
void
_fmpz_poly_gcd(fmpz * res, const fmpz * poly1, slong len1,
const fmpz * poly2, slong len2)
{
if (len1 < 6)
{
_fmpz_poly_gcd_subresultant(res, poly1, len1, poly2, len2);
}
else
{
slong b1, b2;
b1 = _fmpz_vec_max_bits(poly1, len1);
b2 = _fmpz_vec_max_bits(poly2, len2);
b1 = FLINT_ABS(b1);
b2 = FLINT_ABS(b2);
if (b1 + b2 < 2 * FLINT_BITS)
{
if (_fmpz_poly_gcd_heuristic(res, poly1, len1, poly2, len2))
return;
}
_fmpz_poly_gcd_modular(res, poly1, len1, poly2, len2);
}
}
void
fmpz_poly_gcd(fmpz_poly_t res, const fmpz_poly_t poly1,
const fmpz_poly_t poly2)
{
if (poly1->length < poly2->length)
{
fmpz_poly_gcd(res, poly2, poly1);
}
else /* len1 >= len2 >= 0 */
{
const slong len1 = poly1->length;
const slong len2 = poly2->length;
if (len1 == 0) /* len1 = len2 = 0 */
{
fmpz_poly_zero(res);
}
else if (len2 == 0) /* len1 > len2 = 0 */
{
if (fmpz_sgn(poly1->coeffs + (len1 - 1)) > 0)
fmpz_poly_set(res, poly1);
else
fmpz_poly_neg(res, poly1);
}
else /* len1 >= len2 >= 1 */
{
/* all current gcd functions automatically handle aliasing */
fmpz_poly_fit_length(res, len2);
_fmpz_poly_gcd(res->coeffs, poly1->coeffs, len1,
poly2->coeffs, len2);
_fmpz_poly_set_length(res, len2);
_fmpz_poly_normalise(res);
}
}
}
|
