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
/*
Copyright (C) 2015 William Hart
Copyright (C) 2021 Daniel Schultz
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_mod.h"
#include "fmpz_mod_mat.h"
slong fmpz_mod_mat_reduce_row(fmpz_mod_mat_t A, slong * P, slong * L,
slong m, const fmpz_mod_ctx_t ctx)
{
slong n = fmpz_mod_mat_ncols(A, ctx), i, j, r;
fmpz_t h;
fmpz_init(h);
for (i = 0; i < n; i++)
{
if (!fmpz_is_zero(fmpz_mod_mat_entry(A, m, i)))
{
r = P[i];
if (r != -WORD(1))
{
for (j = i + 1; j < L[r]; j++)
{
fmpz_mod_mul(h, fmpz_mod_mat_entry(A, r, j),
fmpz_mod_mat_entry(A, m, i), ctx);
fmpz_mod_sub(fmpz_mod_mat_entry(A, m, j),
fmpz_mod_mat_entry(A, m, j), h, ctx);
}
fmpz_zero(fmpz_mod_mat_entry(A, m, i));
}
else
{
fmpz_mod_inv(h, fmpz_mod_mat_entry(A, m, i), ctx);
fmpz_one(fmpz_mod_mat_entry(A, m, i));
for (j = i + 1; j < L[m]; j++)
fmpz_mod_mul(fmpz_mod_mat_entry(A, m, j),
fmpz_mod_mat_entry(A, m, j), h, ctx);
P[i] = m;
fmpz_clear(h);
return i;
}
}
}
fmpz_clear(h);
return -WORD(1);
}