pqc/external/flint-2.4.3/fmpq_mat/pivot.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) 2011 Fredrik Johansson
******************************************************************************/
#include "fmpq_mat.h"
int
fmpq_mat_pivot(slong * perm, fmpq_mat_t mat, slong r, slong c)
{
slong t, j;
fmpq * u;
if (!fmpq_is_zero(fmpq_mat_entry(mat, r, c)))
return 1;
for (j = r + 1; j < mat->r; j++)
{
if (!fmpq_is_zero(fmpq_mat_entry(mat, j, c)))
{
if (perm)
{
t = perm[j];
perm[j] = perm[r];
perm[r] = t;
}
u = mat->rows[j];
mat->rows[j] = mat->rows[r];
mat->rows[r] = u;
return -1;
}
}
return 0;
}