pqc/external/flint-2.4.3/fmpz_poly_mat/det_interpolate.c
2014-05-24 23:16:06 +02:00

76 lines
2.0 KiB
C

/*=============================================================================
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) 2011 Fredrik Johansson
******************************************************************************/
#include <stdlib.h>
#include "flint.h"
#include "fmpz_poly.h"
#include "fmpz_poly_mat.h"
void
fmpz_poly_mat_det_interpolate(fmpz_poly_t det, const fmpz_poly_mat_t A)
{
slong i, l, n, len;
fmpz_mat_t X;
fmpz * x;
fmpz * d;
n = A->r;
if (n == 0)
{
fmpz_poly_one(det);
return;
}
l = fmpz_poly_mat_max_length(A);
if (l == 0)
{
fmpz_poly_zero(det);
return;
}
/* Bound degree based on Laplace expansion */
len = n*(l - 1) + 1;
x = _fmpz_vec_init(len);
d = _fmpz_vec_init(len);
fmpz_mat_init(X, n, n);
for (i = 0; i < len; i++)
{
fmpz_set_si(x + i, -len/2 + i);
fmpz_poly_mat_evaluate_fmpz(X, A, x + i);
fmpz_mat_det(d + i, X);
}
fmpz_poly_interpolate_fmpz_vec(det, x, d, len);
_fmpz_vec_clear(x, len);
_fmpz_vec_clear(d, len);
fmpz_mat_clear(X);
}