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/*
Copyright (C) 2012 Fredrik Johansson
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "arb.h"
#include "arb_mat.h"
slong
arb_mat_find_pivot_partial(const arb_mat_t mat,
slong start_row, slong end_row, slong c)
{
slong 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;
}