arb/arb_mat/find_pivot_partial.c
Fredrik Johansson d8147d3cc8 add arb_mat
2014-05-14 16:59:09 +02:00

54 lines
1.8 KiB
C

/*=============================================================================
This file is part of ARB.
ARB 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.
ARB 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 ARB; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2012 Fredrik Johansson
******************************************************************************/
#include "arb_mat.h"
long
arb_mat_find_pivot_partial(const arb_mat_t mat,
long start_row, long end_row, long c)
{
long best_row, i;
best_row = -1;
for (i = start_row; i < end_row; i++)
{
if (!arb_contains_zero(arb_mat_entry(mat, i, c)))
{
if (best_row == -1)
{
best_row = i;
}
/* todo: should take the radius into account */
else if (arf_cmpabs(arb_midref(arb_mat_entry(mat, i, c)),
arb_midref(arb_mat_entry(mat, best_row, c))) > 0)
{
best_row = i;
}
}
}
return best_row;
}