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
/*
Copyright (C) 2010 William Hart
Copyright (C) 2010 Sebastian Pancratz
Copyright (C) 2021 Fredrik Johansson
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "fmpz.h"
#include "fmpz_vec.h"
void
_fmpz_vec_content(fmpz_t res, const fmpz * vec, slong len)
{
while (len > 0 && fmpz_is_zero(vec + 0))
{
len--;
vec++;
}
while (len > 1 && fmpz_is_zero(vec + len - 1))
len--;
if (len <= 2)
{
if (len == 0)
fmpz_zero(res);
else if (len == 1)
fmpz_abs(res, vec + 0);
else
fmpz_gcd(res, vec + 0, vec + 1);
return;
}
if (fmpz_is_pm1(vec + 0) || fmpz_is_pm1(vec + len - 1))
{
fmpz_one(res);
return;
}
fmpz_gcd3(res, vec + 0, vec + 1, vec + len - 1);
vec += 2;
len -= 3;
while (len >= 2 && !fmpz_is_one(res))
{
fmpz_gcd3(res, vec + 0, vec + len - 1, res);
vec++;
len -= 2;
}
if (len != 0 && !fmpz_is_one(res))
fmpz_gcd(res, res, vec + 0);
}