pqc/external/flint-2.4.3/fmpz_mat/randntrulike2.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) 2005-2009 Damien Stehle
Copyright (C) 2007 David Cade
Copyright (C) 2010 William Hart
******************************************************************************/
#include "fmpz_mat.h"
void
fmpz_mat_randntrulike2(fmpz_mat_t mat, flint_rand_t state, mp_bitcnt_t bits, ulong q)
{
const slong c = mat->c, r = mat->r, d = r / 2;
slong i, j, k;
fmpz *h;
if ((c != r) || (c != 2 * d))
{
flint_printf("Exception (fmpz_mat_randntrulike2). Ill-formed matrix.\n");
abort();
}
h = _fmpz_vec_init(d);
for (i = 0; i < d; i++)
fmpz_randbits(h + i, state, bits);
for (i = 0; i < d; i++)
{
for (j = 0; j < i; j++)
fmpz_zero(mat->rows[i] + j);
fmpz_set_ui(mat->rows[i] + i, q);
for (j = i + 1; j < d; j++)
fmpz_zero(mat->rows[i] + j);
}
for (i = 0; i < d; i++)
for (j = d; j < c; j++)
fmpz_zero(mat->rows[i] + j);
for (i = d; i < c; i++)
{
for (j = d; j < i; j++)
fmpz_zero(mat->rows[i] + j);
fmpz_one(mat->rows[i] + i);
for (j = i + 1; j < c; j++)
fmpz_zero(mat->rows[i] + j);
}
for (i = d; i < r; i++)
{
for (j = 0; j < d; j++)
{
k = j + i;
while (k >= d)
k -= d;
fmpz_set(mat->rows[i] + j, h + k);
}
}
_fmpz_vec_clear(h, d);
}