pqc/external/flint-2.4.3/fmpq_mat/det.c

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2014-05-18 22:03:37 +00:00
/*=============================================================================
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 "fmpq_mat.h"
void fmpq_mat_det(fmpq_t det, const fmpq_mat_t mat)
{
slong n = mat->r;
if (n == 0)
{
fmpq_set_si(det, WORD(1), WORD(1));
return;
}
else if (n == 1)
{
fmpq_set(det, fmpq_mat_entry(mat, 0, 0));
}
else if (n == 2)
{
fmpq_t t;
fmpq_init(t);
fmpq_mul(t, fmpq_mat_entry(mat, 0, 0), fmpq_mat_entry(mat, 1, 1));
fmpq_submul(t, fmpq_mat_entry(mat, 0, 1), fmpq_mat_entry(mat, 1, 0));
fmpq_set(det, t);
fmpq_clear(t);
}
else
{
fmpz_mat_t num;
fmpz * den;
slong i;
fmpz_mat_init(num, mat->r, mat->c);
den = _fmpz_vec_init(mat->r);
fmpq_mat_get_fmpz_mat_rowwise(num, den, mat);
fmpz_mat_det(&det->num, num);
fmpz_one(&det->den);
for (i = 0; i < mat->r; i++)
fmpz_mul(&det->den, &det->den, den + i);
fmpq_canonicalise(det);
fmpz_mat_clear(num);
_fmpz_vec_clear(den, mat->r);
}
}