mirror of
https://github.com/vale981/arb
synced 2025-03-04 17:01:40 -05:00
61 lines
1.3 KiB
C
61 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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#include "acb_dirichlet.h"
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void
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arb_mat_dct(arb_mat_t res, int kind, slong prec)
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{
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acb_dirichlet_roots_t roots;
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acb_t t;
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arb_t v;
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slong n, r, c, i, j;
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r = arb_mat_nrows(res);
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c = arb_mat_ncols(res);
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n = FLINT_MIN(r, c);
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if (n == 0)
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return;
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acb_dirichlet_roots_init(roots, 4 * n, (r - 1) * c, prec);
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acb_init(t);
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arb_init(v);
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arb_set_ui(v, n);
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arb_rsqrt(v, v, prec);
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if (r > 0)
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{
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for (j = 0; j < c; j++)
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arb_set(arb_mat_entry(res, 0, j), v);
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}
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arb_set_ui(v, n);
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arb_mul_2exp_si(v, v, -1);
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arb_rsqrt(v, v, prec);
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for (i = 1; i < r; i++)
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{
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for (j = 0; j < c; j++)
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{
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acb_dirichlet_root(t, roots, i * (2 * j + 1), prec);
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arb_mul(arb_mat_entry(res, i, j), acb_realref(t), v, prec);
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}
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}
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acb_dirichlet_roots_clear(roots);
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acb_clear(t);
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arb_clear(v);
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}
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