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

69 lines
2.1 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) 2005-2009 Damien Stehle
Copyright (C) 2007 David Cade
Copyright (C) 2010 William Hart
******************************************************************************/
#include <math.h>
#include "fmpz_mat.h"
void
fmpz_mat_randajtai(fmpz_mat_t mat, flint_rand_t state, double alpha)
{
const slong c = mat->c, r = mat->r, d = r;
slong i, j;
fmpz_t tmp;
if (c != r)
{
flint_printf("Exception (fmpz_mat_ajtai): Non-square matrix.\n");
abort();
}
fmpz_init(tmp);
for (i = 0; i < d; i++)
{
mp_bitcnt_t bits = (mp_bitcnt_t) pow((double) (2 * d - i), alpha);
fmpz_one(tmp);
fmpz_mul_2exp(tmp, tmp, bits);
fmpz_sub_ui(tmp, tmp, 1);
fmpz_randm(mat->rows[i] + i, state, tmp);
fmpz_add_ui(mat->rows[i] + i, mat->rows[i] + i, 2);
fmpz_fdiv_q_2exp(mat->rows[i] + i, mat->rows[i] + i, 1);
for (j = i + 1; j <= d; j++)
{
fmpz_randm(mat->rows[j] + i, state, tmp);
if (n_randint(state, 2))
fmpz_neg(mat->rows[j] + i, mat->rows[j] + i);
fmpz_zero(mat->rows[i] + j);
}
}
fmpz_clear(tmp);
}