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/*
Copyright (C) 2012 Fredrik Johansson
This file is part of Arb.
Arb 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 2.1 of the License, or
(at your option) any later version. See <http://www.gnu.org/licenses/>.
*/
#include "acb_mat.h"
int
acb_mat_lu_classical(slong * P, acb_mat_t LU, const acb_mat_t A, slong prec)
{
acb_t d, e;
acb_ptr * a;
slong i, j, m, n, r, row, col;
int result;
if (acb_mat_is_empty(A))
return 1;
m = acb_mat_nrows(A);
n = acb_mat_ncols(A);
acb_mat_set(LU, A);
a = LU->rows;
row = col = 0;
for (i = 0; i < m; i++)
P[i] = i;
acb_init(d);
acb_init(e);
result = 1;
while (row < m && col < n)
{
r = acb_mat_find_pivot_partial(LU, row, m, col);
if (r == -1)
{
result = 0;
break;
}
else if (r != row)
acb_mat_swap_rows(LU, P, row, r);
acb_set(d, a[row] + col);
for (j = row + 1; j < m; j++)
{
acb_div(e, a[j] + col, d, prec);
acb_neg(e, e);
_acb_vec_scalar_addmul(a[j] + col,
a[row] + col, n - col, e, prec);
acb_zero(a[j] + col);
acb_neg(a[j] + row, e);
}
row++;
col++;
}
acb_clear(d);
acb_clear(e);
return result;
}
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