1 /*
2 Copyright (C) 2011 Fredrik Johansson
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 <stdlib.h>
13 #include "flint.h"
14 #include "fmpz_poly.h"
15 #include "fmpz_poly_mat.h"
16
17 void
fmpz_poly_mat_det_interpolate(fmpz_poly_t det,const fmpz_poly_mat_t A)18 fmpz_poly_mat_det_interpolate(fmpz_poly_t det, const fmpz_poly_mat_t A)
19 {
20 slong i, l, n, len;
21
22 fmpz_mat_t X;
23 fmpz * x;
24 fmpz * d;
25
26 n = A->r;
27
28 if (n == 0)
29 {
30 fmpz_poly_one(det);
31 return;
32 }
33
34 l = fmpz_poly_mat_max_length(A);
35
36 if (l == 0)
37 {
38 fmpz_poly_zero(det);
39 return;
40 }
41
42 /* Bound degree based on Laplace expansion */
43 len = n*(l - 1) + 1;
44
45 x = _fmpz_vec_init(len);
46 d = _fmpz_vec_init(len);
47 fmpz_mat_init(X, n, n);
48
49 for (i = 0; i < len; i++)
50 {
51 fmpz_set_si(x + i, -len/2 + i);
52 fmpz_poly_mat_evaluate_fmpz(X, A, x + i);
53 fmpz_mat_det(d + i, X);
54 }
55
56 fmpz_poly_interpolate_fmpz_vec(det, x, d, len);
57
58 _fmpz_vec_clear(x, len);
59 _fmpz_vec_clear(d, len);
60 fmpz_mat_clear(X);
61 }
62