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/*
Copyright (C) 2016 Arb authors
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"
void
arb_mat_solve_cho_precomp(arb_mat_t X,
const arb_mat_t L, const arb_mat_t B, slong prec)
{
slong i, j, c, n, m;
n = arb_mat_nrows(X);
m = arb_mat_ncols(X);
arb_mat_set(X, B);
for (c = 0; c < m; c++)
{
/* solve Ly = b */
for (i = 0; i < n; i++)
{
for (j = 0; j < i; j++)
{
arb_submul(arb_mat_entry(X, i, c),
arb_mat_entry(L, i, j), arb_mat_entry(X, j, c), prec);
}
arb_div(arb_mat_entry(X, i, c), arb_mat_entry(X, i, c),
arb_mat_entry(L, i, i), prec);
}
/* solve Ux = y */
for (i = n - 1; i >= 0; i--)
{
for (j = i + 1; j < n; j++)
{
arb_submul(arb_mat_entry(X, i, c),
arb_mat_entry(L, j, i), arb_mat_entry(X, j, c), prec);
}
arb_div(arb_mat_entry(X, i, c), arb_mat_entry(X, i, c),
arb_mat_entry(L, i, i), prec);
}
}
}