arb/dlog/factor_group.c
2016-09-06 16:23:12 +02:00

53 lines
1.2 KiB
C

/*
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 "dlog.h"
/* group components up to bound and return cofactor */
void
dlog_n_factor_group(n_factor_t * fac, ulong bound)
{
int i, j, k;
ulong m[FLINT_MAX_FACTORS_IN_LIMB];
ulong c = 1;
i = 0;
for (k = fac->num - 1; k >= 0; k--)
{
ulong qe = n_pow(fac->p[k], fac->exp[k]);
if (qe > bound)
c *= qe;
else
{
/* try to insert somewhere in m */
for (j = 0; j < i && (m[j] * qe > bound); j++);
if (j == i)
m[i++] = qe;
else
m[j] *= qe;
}
}
for (j = 0; j < i; j++)
{
fac->p[j] = m[j];
fac->exp[j] = DLOG_G_SMALL;
}
if (c > 1)
{
fac->p[i] = c;
fac->exp[i] = DLOG_G_BIG;
i++;
}
fac->num = i;
}