1 /*
2 Copyright (C) 2014 Alex J. Best
3
4 This file is part of FLINT.
5
6 FLINT is free software: you can redistribute it and/or modify it under
7 the terms of the GNU Lesser General Public License (LGPL) as published
8 by the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version. See <http://www.gnu.org/licenses/>.
10 */
11
12 #include "fmpz_mat.h"
13
fmpz_mat_is_in_snf(const fmpz_mat_t A)14 int fmpz_mat_is_in_snf(const fmpz_mat_t A)
15 {
16 slong i, j;
17 for (i = 0; i < A->r; i++)
18 {
19 for (j = 0; j < A->c; j++)
20 {
21 if (i == j)
22 {
23 if (fmpz_sgn(fmpz_mat_entry(A, i, i)) < 0)
24 return 0;
25 if (i > 0)
26 {
27 if (!fmpz_is_zero(fmpz_mat_entry(A, i, i)) &&
28 fmpz_is_zero(fmpz_mat_entry(A, i - 1, i - 1)))
29 return 0;
30 if (!fmpz_divisible(fmpz_mat_entry(A, i, i),
31 fmpz_mat_entry(A, i - 1, i - 1)))
32 return 0;
33 }
34 }
35 else if (!fmpz_is_zero(fmpz_mat_entry(A, i, j)))
36 return 0;
37 }
38 }
39
40 return 1;
41 }
42