arb/acb_dirichlet/conrey_log.c
2016-09-06 15:32:23 +02:00

51 lines
1.4 KiB
C

/*
Copyright (C) 2015 Jonathan Bober
Copyright (C) 2016 Fredrik Johansson
Copyright (C) 2016 Pascal Molin
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_dirichlet.h"
/* TODO: use dlog module instead of n_discrete_log_bsgs */
/* assume m is invertible */
void
acb_dirichlet_conrey_log(acb_dirichlet_conrey_t x, const acb_dirichlet_group_t G, ulong m)
{
ulong k, pk, gk;
/* even part */
if (G->neven >= 1)
{
x->log[0] = (m % 4 == 3);
if (G->neven == 2)
{
ulong m2 = (x->log[0]) ? -m % G->q_even : m % G->q_even;
if (G->P[1].dlog == NULL)
x->log[1] = n_discrete_log_bsgs(m2, 5, G->q_even);
else
x->log[1] = dlog_precomp(G->P[1].dlog, m2);
}
}
/* odd part */
for (k = G->neven; k < G->num; k++)
{
if (G->P[k].dlog == NULL)
{
pk = G->P[k].pe.n;
gk = G->P[k].g;
x->log[k] = n_discrete_log_bsgs(m % pk, gk, pk);
}
else
{
x->log[k] = dlog_precomp(G->P[k].dlog, m % G->P[k].pe.n);
}
}
/* keep value m */
x->n = m;
}