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/*
Copyright (C) 2009, 2010 William Hart
Copyright (C) 2009, 2010 Andy Novocin
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 "fmpz.h"
#include "fmpz_mat.h"
#include "fmpz_lll.h"
int
fmpz_lll_with_removal_ulll(fmpz_mat_t FM, fmpz_mat_t UM, slong new_size,
const fmpz_t gs_B, const fmpz_lll_t fl)
{
int newd;
if (fl->rt == Z_BASIS)
{
slong r, c, mbits, prev_mbits, i, j;
int full_prec = 1, done = 0, is_U_I;
fmpz_mat_t U, big_td, trunc_data;
r = FM->r;
c = FM->c;
mbits = fmpz_mat_max_bits(FM);
mbits = FLINT_ABS(mbits);
prev_mbits = mbits;
fmpz_mat_init(big_td, r, c + r);
fmpz_mat_init(trunc_data, r, c);
if (mbits > new_size)
{
full_prec = 0;
/* do some truncating */
fmpz_mat_scalar_tdiv_q_2exp(trunc_data, FM,
(ulong) (mbits - new_size));
/* make a large lattice which has identity in one corner and trunc_data in the other */
for (i = 0; i < r; i++)
{
fmpz_one(fmpz_mat_entry(big_td, i, i));
for (j = r; j < r + c; j++)
fmpz_set(fmpz_mat_entry(big_td, i, j),
fmpz_mat_entry(trunc_data, i, j - r));
}
}
else
{
full_prec = 1;
}
while (done == 0)
{
if (full_prec == 0)
{
fmpz_lll_wrapper_with_removal_knapsack(big_td, UM, gs_B, fl);
}
else
{
newd =
fmpz_lll_wrapper_with_removal_knapsack(FM, UM, gs_B, fl);
}
if (full_prec == 1)
done = 1;
else
{
/* get U and compare it to the identity */
fmpz_mat_window_init(U, big_td, 0, 0, r, r);
is_U_I = fmpz_mat_is_one(U);
if (is_U_I == 0)
{
fmpz_mat_mul(FM, U, FM);
}
mbits = fmpz_mat_max_bits(FM);
mbits = FLINT_ABS(mbits);
/* make this condition better? */
if ((mbits - new_size > 0)
&& (mbits <= prev_mbits - (slong) (new_size / 4))
&& is_U_I == 0)
{
/* do some truncating */
fmpz_mat_scalar_tdiv_q_2exp(trunc_data, FM,
(ulong) (mbits - new_size));
/* keep with the big_td concept */
for (i = 0; i < r; i++)
{
for (j = 0; j < i; j++)
fmpz_zero(fmpz_mat_entry(big_td, i, j));
fmpz_one(fmpz_mat_entry(big_td, i, i));
for (j = i + 1; j < r; j++)
fmpz_zero(fmpz_mat_entry(big_td, i, j));
for (j = r; j < r + c; j++)
fmpz_set(fmpz_mat_entry
(big_td, i, j),
fmpz_mat_entry(trunc_data, i, j - r));
}
}
else
{
/* can switch to FM, no need for a new identity */
full_prec = 1;
}
prev_mbits = mbits;
fmpz_mat_window_clear(U);
}
}
fmpz_mat_clear(trunc_data);
fmpz_mat_clear(big_td);
}
else
{
newd = fmpz_lll_wrapper_with_removal_knapsack(FM, UM, gs_B, fl);
}
return newd;
}