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

56 lines
1.7 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) 2010,2011 Fredrik Johansson
******************************************************************************/
#include "flint.h"
#include "ulong_extras.h"
#include "nmod_mat.h"
#include "nmod_vec.h"
#include "perm.h"
int
nmod_mat_randpermdiag(nmod_mat_t mat, flint_rand_t state,
mp_srcptr diag, slong n)
{
int parity;
slong i;
slong * rows;
slong * cols;
rows = _perm_init(mat->r);
cols = _perm_init(mat->c);
parity = _perm_randtest(rows, mat->r, state);
parity ^= _perm_randtest(cols, mat->c, state);
nmod_mat_zero(mat);
for (i = 0; i < n; i++)
nmod_mat_entry(mat, rows[i], cols[i]) = diag[i];
_perm_clear(rows);
_perm_clear(cols);
return parity;
}