mirror of
https://github.com/vale981/arb
synced 2025-03-06 01:41:39 -05:00
56 lines
1.3 KiB
C
56 lines
1.3 KiB
C
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/*
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Copyright (C) 2018 Fredrik Johansson
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This file is part of Arb.
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Arb is free software: you can redistribute it and/or modify it under
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the terms of the GNU Lesser General Public License (LGPL) as published
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by the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version. See <http://www.gnu.org/licenses/>.
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*/
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#include "arb_mat.h"
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void
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_arb_mat_diag_prod(arb_t res, const arb_mat_t A, slong a, slong b, slong prec)
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{
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if (b - a == 0)
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{
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arb_one(res);
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}
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else if (b - a == 1)
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{
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arb_set_round(res, arb_mat_entry(A, a, a), prec);
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}
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else
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{
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slong i;
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arb_mul(res, arb_mat_entry(A, a, a), arb_mat_entry(A, a + 1, a + 1), prec);
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for (i = a + 2; i < b; i++)
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arb_mul(res, res, arb_mat_entry(A, i, i), prec);
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/* no advantage? */
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/*
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arb_t t;
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arb_init(t);
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_arb_mat_diag_prod(t, A, a, a + (b - a) / 2, prec);
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_arb_mat_diag_prod(res, A, a + (b - a) / 2, b, prec);
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arb_mul(res, res, t, prec);
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arb_clear(t);
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*/
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}
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}
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void
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arb_mat_diag_prod(arb_t res, const arb_mat_t A, slong prec)
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{
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slong m, n;
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m = arb_mat_nrows(A);
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n = arb_mat_nrows(A);
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_arb_mat_diag_prod(res, A, 0, FLINT_MIN(m, n), prec);
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}
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