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/*
Copyright (C) 2010 William Hart
Copyright (C) 2010 Fredrik Johansson
Copyright (C) 2014 Abhinav Baid
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 <math.h>
#include "d_vec.h"
#include "fmpz.h"
#include "fmpz_vec.h"
#include "fmpz_mat.h"
#include "fmpz_lll.h"
double
fmpz_lll_heuristic_dot(const double *vec1, const double *vec2, slong len2,
const fmpz_mat_t B, slong k, slong j, slong exp_adj)
{
double sum = _d_vec_dot(vec1, vec2, len2);
double tmp = _d_vec_norm(vec1, len2);
double tmp2 = _d_vec_norm(vec2, len2);
tmp = tmp*tmp2 * ldexp(1.0, -70);
tmp2 = sum*sum;
if (tmp2 <= tmp)
{
slong exp;
fmpz_t sp;
fmpz_init(sp);
_fmpz_vec_dot(sp, fmpz_mat_row(B, k), fmpz_mat_row(B, j), len2);
sum = fmpz_get_d_2exp(&exp, sp);
sum = ldexp(sum, sum - exp_adj);
fmpz_clear(sp);
}
return sum;
}