arb/acb_elliptic/zeta.c

81 lines
2.2 KiB
C

/*
Copyright (C) 2017 Fredrik Johansson
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_elliptic.h"
#include "acb_modular.h"
/* eta1 = (-1/6) theta1'''(0) / theta1'(0) */
static void
eta1(acb_t res, acb_t theta1, const acb_t tau, slong prec)
{
acb_ptr theta;
acb_t z;
acb_init(z);
theta = _acb_vec_init(16);
acb_modular_theta_jet(theta,
theta + 4, theta + 8, theta + 12, z, tau, 4, prec);
if (theta1 != NULL)
acb_set(theta1, theta + 1);
acb_div(res, theta + 3, theta + 1, prec);
acb_neg(res, res);
_acb_vec_clear(theta, 16);
acb_clear(z);
}
/* zeta(z) = 2 eta1 z + theta1'(z,q) / theta1(z,q) */
void
acb_elliptic_zeta(acb_t res, const acb_t z, const acb_t tau, slong prec)
{
acb_ptr t;
int real;
real = acb_is_real(z) && arb_is_int_2exp_si(acb_realref(tau), -1) &&
arb_is_positive(acb_imagref(tau));
t = _acb_vec_init(8);
acb_modular_theta_jet(t, t + 2, t + 4, t + 6, z, tau, 2, prec);
eta1(t + 2, NULL, tau, prec);
acb_mul_2exp_si(t + 2, t + 2, 1);
acb_mul(t + 2, t + 2, z, prec);
acb_div(t, t + 1, t, prec);
acb_add(res, t, t + 2, prec);
if (real)
arb_zero(acb_imagref(res));
_acb_vec_clear(t, 8);
}
/* sigma(z) = exp(eta1 z^2) theta1(z) / theta1'(0) */
void
acb_elliptic_sigma(acb_t res, const acb_t z, const acb_t tau, slong prec)
{
acb_ptr t;
int real;
real = acb_is_real(z) && arb_is_int_2exp_si(acb_realref(tau), -1) &&
arb_is_positive(acb_imagref(tau));
t = _acb_vec_init(8);
acb_modular_theta_jet(t, t + 2, t + 4, t + 6, z, tau, 2, prec);
eta1(t + 2, t + 3, tau, prec);
acb_mul(t + 4, z, z, prec);
acb_mul(t + 2, t + 2, t + 4, prec);
acb_exp(t + 2, t + 2, prec);
acb_div(t, t, t + 3, prec);
acb_mul(res, t, t + 2, prec);
if (real)
arb_zero(acb_imagref(res));
_acb_vec_clear(t, 8);
}