arb/acb_modular/theta_const_sum_rs.c
2015-10-13 18:02:33 +02:00

226 lines
6.7 KiB
C

/*=============================================================================
This file is part of ARB.
ARB is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
ARB is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with ARB; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2015 Fredrik Johansson
******************************************************************************/
#include "acb_modular.h"
double mag_get_log2_d_approx(const mag_t x);
static const int square_best_m[] = {
2, 3, 4, 8, 12, 16, 32, 48, 80, 96,
112, 144, 240, 288, 336, 480, 560, 576, 720, 1008,
1440, 1680, 2016, 2640, 2880, 3600, 4032, 5040, 7920, 9360,
10080, 15840, 18480, 20160, 25200, 31680, 37440, 39600, 44352, 50400,
55440, 65520, 85680, 95760, 102960, 110880, 131040, 171360, 191520, 205920,
221760, 262080, 277200, 327600, 383040, 411840, 514800, 554400, 655200, 720720,
942480, 0
};
static const int square_best_m_residues[] = {
2, 2, 2, 3, 4, 4, 7, 8, 12, 14,
16, 16, 24, 28, 32, 42, 48, 48, 48, 64,
84, 96, 112, 144, 144, 176, 192, 192, 288, 336,
336, 504, 576, 576, 704, 864, 1008, 1056, 1152, 1232,
1152, 1344, 1728, 1920, 2016, 2016, 2352, 3024, 3360, 3528,
3456, 4032, 4224, 4928, 5760, 6048, 7392, 7392, 8624, 8064,
10368, 0
};
static const int trigonal_best_m[] = {
2, 6, 10, 14, 18, 30, 42, 66, 70, 90,
126, 198, 210, 330, 390, 450, 630, 990, 1170, 1386,
1638, 2142, 2310, 2730, 3150, 4950, 5850, 6930, 8190, 10710,
11970, 12870, 16830, 18018, 23562, 26334, 27846, 30030, 34650, 40950,
53550, 59850, 64350, 84150, 90090, 117810, 131670, 139230, 155610, 188370,
203490, 218790, 244530, 270270, 296010, 306306, 342342, 414414, 447678, 450450,
589050, 658350, 696150, 778050, 941850, 0
};
static const int trigonal_best_m_residues[] = {
1, 2, 3, 4, 4, 6, 8, 12, 12, 12,
16, 24, 24, 36, 42, 44, 48, 72, 84, 96,
112, 144, 144, 168, 176, 264, 308, 288, 336, 432,
480, 504, 648, 672, 864, 960, 1008, 1008, 1056, 1232,
1584, 1760, 1848, 2376, 2016, 2592, 2880, 3024, 3360, 4032,
4320, 4536, 5040, 5544, 6048, 6048, 6720, 8064, 8640, 7392,
9504, 10560, 11088, 12320, 14784, 0,
};
long
acb_modular_rs_optimal_m(const int * best_ms, const int * num_residues, long N)
{
long i, m, cost, best_i, best_m, best_cost;
best_i = 0;
best_m = best_ms[0];
best_cost = LONG_MAX;
for (i = 0; (m = best_ms[i]) != 0; i++)
{
cost = N / m + num_residues[i];
if (i == 0 || cost < best_cost)
{
best_i = i;
best_cost = cost;
best_m = m;
}
}
/* printf("N = %ld, best_m = %ld, best_cost = %ld, s(m) = %d\n",
N, best_m, best_cost, num_residues[best_i]); */
i = best_i;
return best_m;
}
void
acb_modular_theta_const_sum_rs(acb_t theta2, acb_t theta3, acb_t theta4,
const acb_t q, long N, long prec)
{
long * tab;
long k, term_prec, i, e, eprev;
long M, m2, m3, num_square, num_trigonal;
double log2q_approx, log2term_approx;
acb_ptr qpow;
acb_t tmp1, tmp2;
mag_t qmag;
mag_init(qmag);
acb_get_mag(qmag, q);
log2q_approx = mag_get_log2_d_approx(qmag);
mag_clear(qmag);
acb_init(tmp1);
acb_init(tmp2);
/* choose rectangular splitting parameters */
m2 = acb_modular_rs_optimal_m(trigonal_best_m, trigonal_best_m_residues, N);
m3 = acb_modular_rs_optimal_m(square_best_m, square_best_m_residues, N);
M = FLINT_MAX(m2, m3) + 1;
/* build addition sequence */
tab = flint_calloc(M, sizeof(long));
for (k = 0; k*(k+1) < N; k++)
tab[(k*(k+1)) % m2] = -1;
num_trigonal = k;
for (k = 0; k*k < N; k++)
tab[(k*k) % m3] = -1;
num_square = k;
tab[m2] = -1;
tab[m3] = -1;
/* compute powers in addition sequence */
qpow = _acb_vec_init(M);
acb_modular_fill_addseq(tab, M);
for (k = 0; k < M; k++)
{
if (k == 0)
{
acb_one(qpow + k);
}
else if (k == 1)
{
acb_set_round(qpow + k, q, prec);
}
else if (tab[k] != 0)
{
log2term_approx = k * log2q_approx;
term_prec = FLINT_MIN(FLINT_MAX(prec + log2term_approx + 16.0, 16.0), prec);
acb_mul_approx(qpow + k, tmp1, tmp2, qpow + tab[k], qpow + k - tab[k], term_prec, prec);
}
}
/* compute theta2 */
acb_zero(theta2);
term_prec = prec;
for (k = num_trigonal - 1; k >= 0; k--)
{
e = k * (k + 1); /* exponent */
eprev = (k + 1) * (k + 2);
log2term_approx = e * log2q_approx;
term_prec = FLINT_MIN(FLINT_MAX(prec + log2term_approx + 16.0, 16.0), prec);
/* giant steps */
for (i = e / m2; i < eprev / m2; i++)
{
if (!acb_is_zero(theta2))
acb_mul_approx(theta2, tmp1, tmp2, theta2, qpow + m2, term_prec, prec);
}
acb_add(theta2, theta2, qpow + (e % m2), prec);
}
acb_mul_2exp_si(theta2, theta2, 1);
/* compute theta3, theta4 */
acb_zero(theta3);
acb_zero(theta4);
term_prec = prec;
for (k = num_square - 1; k >= 0; k--)
{
e = k * k; /* exponent */
eprev = (k + 1) * (k + 1);
log2term_approx = e * log2q_approx;
term_prec = FLINT_MIN(FLINT_MAX(prec + log2term_approx + 16.0, 16.0), prec);
/* giant steps */
for (i = e / m3; i < eprev / m3; i++)
{
if (!acb_is_zero(theta3))
acb_mul_approx(theta3, tmp1, tmp2, theta3, qpow + m3, term_prec, prec);
if (!acb_is_zero(theta4))
acb_mul_approx(theta4, tmp1, tmp2, theta4, qpow + m3, term_prec, prec);
}
if (k == 0)
{
acb_mul_2exp_si(theta3, theta3, 1);
acb_mul_2exp_si(theta4, theta4, 1);
}
acb_add(theta3, theta3, qpow + (e % m3), prec);
if (k % 2 == 0)
acb_add(theta4, theta4, qpow + (e % m3), prec);
else
acb_sub(theta4, theta4, qpow + (e % m3), prec);
}
acb_clear(tmp1);
acb_clear(tmp2);
_acb_vec_clear(qpow, M);
flint_free(tab);
}