mirror of
https://github.com/vale981/arb
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51 lines
1.4 KiB
C
51 lines
1.4 KiB
C
/*
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Copyright (C) 2015 Jonathan Bober
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Copyright (C) 2016 Fredrik Johansson
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Copyright (C) 2016 Pascal Molin
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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 "dlog.h"
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#include "dirichlet.h"
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/* assume m is invertible */
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void
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dirichlet_char_log(dirichlet_char_t x, const dirichlet_group_t G, ulong m)
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{
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slong k;
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/* even part */
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if (G->neven >= 1)
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{
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x->log[0] = (m % 4 == 3);
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if (G->neven == 2)
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{
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ulong m2 = (x->log[0]) ? -m % G->q_even : m % G->q_even;
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if (G->P[1].dlog == NULL)
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x->log[1] = dlog_mod2e_1mod4(m2, G->P[1].e,
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nmod_inv(5, G->P[1].pe), G->P[1].pe);
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else
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x->log[1] = dlog_precomp(G->P[1].dlog, m2);
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}
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}
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/* odd part */
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for (k = G->neven; k < G->num; k++)
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{
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dirichlet_prime_group_struct P = G->P[k];
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if (P.dlog == NULL)
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{
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x->log[k] = dlog_once(m % P.pe.n, P.g, P.pe, P.phi.n);
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}
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else
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{
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x->log[k] = dlog_precomp(P.dlog, m % P.pe.n);
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}
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}
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/* keep value m */
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x->n = m;
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}
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