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/*
Copyright (C) 2011 Fredrik Johansson
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_mat.h"
#include "fmpq.h"
void
fmpz_mat_det_divisor(fmpz_t d, const fmpz_mat_t A)
{
fmpz_mat_t X, B;
fmpz_t t, u, v, mod;
slong i, n;
int success;
n = A->r;
fmpz_mat_init(B, n, 1);
fmpz_mat_init(X, n, 1);
fmpz_init(t);
fmpz_init(u);
fmpz_init(v);
fmpz_init(mod);
/* Create a "random" vector */
for (i = 0; i < n; i++)
{
fmpz_set_si(fmpz_mat_entry(B, i, 0), 2*(i % 2) - 1);
}
success = fmpz_mat_solve_dixon(X, mod, A, B);
if (success)
{
fmpz_one(d);
for (i = 0; i < n; i++)
{
fmpz_mul(t, d, fmpz_mat_entry(X, i, 0));
fmpz_fdiv_qr(u, t, t, mod);
if (!_fmpq_reconstruct_fmpz(u, v, t, mod))
{
flint_throw(FLINT_ERROR, "(fmpz_mat_det_divisor): Rational reconstruction failed.\n");
}
fmpz_mul(d, v, d);
}
}
else
{
fmpz_zero(d);
}
fmpz_mat_clear(B);
fmpz_mat_clear(X);
fmpz_clear(t);
fmpz_clear(u);
fmpz_clear(v);
fmpz_clear(mod);
}