void
acb_sinc_pi(acb_t res, const acb_t x, slong prec)
{
mag_t m;
acb_t t;
if (acb_is_zero(x))
{
acb_one(res);
return;
}
mag_init(m);
acb_init(t);
acb_get_mag_lower(m, x);
if (mag_cmp_2exp_si(m, -1) > 0)
{
acb_const_pi(t, prec + 4);
acb_mul(t, t, x, prec + 4);
acb_sin_pi(res, x, prec + 4);
acb_div(res, res, t, prec);
}
else
{
acb_const_pi(t, prec + 4);
acb_mul(t, t, x, prec + 4);
acb_sinc(res, t, prec);
}
mag_clear(m);
acb_clear(t);
}
void
_acb_poly_div_root(acb_ptr Q, acb_t R, acb_srcptr A,
slong len, const acb_t c, slong prec)
{
acb_t r, t;
slong i;
if (len < 2)
{
acb_zero(R);
return;
}
acb_init(r);
acb_init(t);
acb_set(t, A + len - 2);
acb_set(Q + len - 2, A + len - 1);
acb_set(r, Q + len - 2);
/* TODO: avoid the extra assignments (but still support aliasing) */
for (i = len - 2; i > 0; i--)
{
acb_mul(r, r, c, prec);
acb_add(r, r, t, prec);
acb_set(t, A + i - 1);
acb_set(Q + i - 1, r);
}
acb_mul(r, r, c, prec);
acb_add(R, r, t, prec);
acb_clear(r);
acb_clear(t);
}
void
acb_lambertw_initial_asymp(acb_t w, const acb_t z, const fmpz_t k, slong prec)
{
acb_t L1, L2, t;
acb_init(L1);
acb_init(L2);
acb_init(t);
acb_const_pi(L2, prec);
acb_mul_2exp_si(L2, L2, 1);
acb_mul_fmpz(L2, L2, k, prec);
acb_mul_onei(L2, L2);
acb_log(L1, z, prec);
acb_add(L1, L1, L2, prec);
acb_log(L2, L1, prec);
/* L1 - L2 + L2/L1 + L2(L2-2)/(2 L1^2) */
acb_inv(t, L1, prec);
acb_mul_2exp_si(w, L2, 1);
acb_submul(w, L2, L2, prec);
acb_neg(w, w);
acb_mul(w, w, t, prec);
acb_mul_2exp_si(w, w, -1);
acb_add(w, w, L2, prec);
acb_mul(w, w, t, prec);
acb_sub(w, w, L2, prec);
acb_add(w, w, L1, prec);
acb_clear(L1);
acb_clear(L2);
acb_clear(t);
}
/* REAL: erf(x) = 2x/sqrt(pi) * exp(-x^2) 1F1(1, 3/2, x^2) */
void
acb_hypgeom_erf_1f1b(acb_t res, const acb_t z, slong prec)
{
acb_t a, b, t, w;
acb_init(a);
acb_init(b);
acb_init(t);
acb_init(w);
acb_set_ui(b, 3);
acb_mul_2exp_si(b, b, -1);
acb_mul(w, z, z, prec);
acb_hypgeom_pfq_direct(t, a, 0, b, 1, w, -1, prec);
acb_neg(w, w);
acb_exp(w, w, prec);
acb_mul(t, t, w, prec);
acb_mul(t, t, z, prec);
arb_const_sqrt_pi(acb_realref(w), prec);
acb_div_arb(t, t, acb_realref(w), prec);
acb_mul_2exp_si(res, t, 1);
acb_clear(a);
acb_clear(b);
acb_clear(t);
acb_clear(w);
}
void
acb_modular_elliptic_e(acb_t res, const acb_t m, long prec)
{
if (acb_is_zero(m))
{
acb_const_pi(res, prec);
acb_mul_2exp_si(res, res, -1);
}
else if (acb_is_one(m))
{
acb_one(res);
}
else
{
acb_struct t[2];
acb_init(t + 0);
acb_init(t + 1);
acb_modular_elliptic_k_cpx(t, m, 2, prec);
acb_mul(t + 1, t + 1, m, prec);
acb_mul_2exp_si(t + 1, t + 1, 1);
acb_add(t, t, t + 1, prec);
acb_sub_ui(t + 1, m, 1, prec);
acb_mul(res, t, t + 1, prec);
acb_neg(res, res);
acb_clear(t + 0);
acb_clear(t + 1);
}
}
/* todo: remove radii */
void
acb_lambertw_halley_step(acb_t res, acb_t ew, const acb_t z, const acb_t w, slong prec)
{
acb_t t, u, v;
acb_init(t);
acb_init(u);
acb_init(v);
acb_exp(ew, w, prec);
acb_add_ui(u, w, 2, prec);
acb_add_ui(v, w, 1, prec);
acb_mul_2exp_si(v, v, 1);
acb_div(v, u, v, prec);
acb_mul(t, ew, w, prec);
acb_sub(u, t, z, prec);
acb_mul(v, v, u, prec);
acb_neg(v, v);
acb_add(v, v, t, prec);
acb_add(v, v, ew, prec);
acb_div(t, u, v, prec);
acb_sub(t, w, t, prec);
acb_swap(res, t);
acb_clear(t);
acb_clear(u);
acb_clear(v);
}
/* f(z) = erf(z/sqrt(0.0002)*0.5 +1.5)*exp(-z), example provided by Silviu-Ioan Filip */
int
f_erf_bent(acb_ptr res, const acb_t z, void * param, slong order, slong prec)
{
acb_t t;
if (order > 1)
flint_abort(); /* Would be needed for Taylor method. */
acb_init(t);
acb_set_ui(t, 1250);
acb_sqrt(t, t, prec);
acb_mul(t, t, z, prec);
acb_set_d(res, 1.5);
acb_add(res, res, t, prec);
acb_hypgeom_erf(res, res, prec);
acb_neg(t, z);
acb_exp(t, t, prec);
acb_mul(res, res, t, prec);
acb_clear(t);
return 0;
}
/* f(z) = |z^4 + 10z^3 + 19z^2 - 6z - 6| exp(z) (for real z) --
Helfgott's integral on MathOverflow */
int
f_helfgott(acb_ptr res, const acb_t z, void * param, slong order, slong prec)
{
if (order > 1)
flint_abort(); /* Would be needed for Taylor method. */
acb_add_si(res, z, 10, prec);
acb_mul(res, res, z, prec);
acb_add_si(res, res, 19, prec);
acb_mul(res, res, z, prec);
acb_add_si(res, res, -6, prec);
acb_mul(res, res, z, prec);
acb_add_si(res, res, -6, prec);
acb_real_abs(res, res, order != 0, prec);
if (acb_is_finite(res))
{
acb_t t;
acb_init(t);
acb_exp(t, z, prec);
acb_mul(res, res, t, prec);
acb_clear(t);
}
return 0;
}
void
acb_hypgeom_bessel_j_asymp_prefactors(acb_t Ap, acb_t Am, acb_t C,
const acb_t nu, const acb_t z, long prec)
{
if (arb_is_positive(acb_realref(z)))
{
acb_t t, u;
acb_init(t);
acb_init(u);
/* -(2nu+1)/4 * pi + z */
acb_mul_2exp_si(t, nu, 1);
acb_add_ui(t, t, 1, prec);
acb_mul_2exp_si(t, t, -2);
acb_neg(t, t);
acb_const_pi(u, prec);
acb_mul(t, t, u, prec);
acb_add(t, t, z, prec);
acb_mul_onei(t, t);
acb_exp_invexp(Ap, Am, t, prec);
/* (2 pi z)^(-1/2) */
acb_const_pi(C, prec);
acb_mul_2exp_si(C, C, 1);
acb_mul(C, C, z, prec);
acb_rsqrt(C, C, prec);
acb_clear(t);
acb_clear(u);
return;
}
acb_hypgeom_bessel_j_asymp_prefactors_fallback(Ap, Am, C, nu, z, prec);
}
void
_acb_poly_sin_cos_pi_series(acb_ptr s, acb_ptr c, const acb_srcptr h, slong hlen, slong n, slong prec)
{
hlen = FLINT_MIN(hlen, n);
if (hlen == 1)
{
acb_sin_cos_pi(s, c, h, prec);
_acb_vec_zero(s + 1, n - 1);
_acb_vec_zero(c + 1, n - 1);
}
else if (n == 2)
{
acb_t t;
acb_init(t);
acb_const_pi(t, prec);
acb_mul(t, t, h + 1, prec);
acb_sin_cos_pi(s, c, h, prec);
acb_mul(s + 1, c, t, prec);
acb_neg(t, t);
acb_mul(c + 1, s, t, prec);
acb_clear(t);
}
else if (hlen < TANGENT_CUTOFF)
_acb_poly_sin_cos_series_basecase(s, c, h, hlen, n, prec, 1);
else
_acb_poly_sin_cos_series_tangent(s, c, h, hlen, n, prec, 1);
}
void
acb_polygamma(acb_t res, const acb_t s, const acb_t z, long prec)
{
if (acb_is_zero(s))
{
acb_digamma(res, z, prec);
}
else if (acb_is_int(s) && arb_is_positive(acb_realref(s)))
{
acb_t t, u;
acb_init(t);
acb_init(u);
acb_add_ui(t, s, 1, prec);
acb_gamma(u, t, prec);
acb_hurwitz_zeta(t, t, z, prec);
if (arf_is_int_2exp_si(arb_midref(acb_realref(s)), 1))
acb_neg(t, t);
acb_mul(res, t, u, prec);
acb_clear(t);
acb_clear(u);
}
else
{
acb_t t, u;
acb_struct v[2];
acb_init(t);
acb_init(u);
acb_init(v);
acb_init(v + 1);
/* u = psi(-s) + gamma */
acb_neg(t, s);
acb_digamma(u, t, prec);
arb_const_euler(acb_realref(v), prec);
arb_add(acb_realref(u), acb_realref(u), acb_realref(v), prec);
acb_add_ui(t, s, 1, prec);
_acb_poly_zeta_cpx_series(v, t, z, 0, 2, prec);
acb_addmul(v + 1, v, u, prec);
acb_neg(t, s);
acb_rgamma(u, t, prec);
acb_mul(res, v + 1, u, prec);
acb_clear(v);
acb_clear(v + 1);
acb_clear(t);
acb_clear(u);
}
}
void
acb_modular_lambda(acb_t r, const acb_t tau, long prec)
{
psl2z_t g;
arf_t one_minus_eps;
acb_t tau_prime, q;
acb_struct thetas[4];
int R[4], S[4], C;
int Rsum, qpower;
psl2z_init(g);
arf_init(one_minus_eps);
acb_init(tau_prime);
acb_init(q);
acb_init(thetas + 0);
acb_init(thetas + 1);
acb_init(thetas + 2);
acb_init(thetas + 3);
arf_set_ui_2exp_si(one_minus_eps, 63, -6);
acb_modular_fundamental_domain_approx(tau_prime, g, tau,
one_minus_eps, prec);
acb_modular_theta_transform(R, S, &C, g);
acb_exp_pi_i(q, tau_prime, prec);
acb_modular_theta_const_sum(thetas + 1, thetas + 2, thetas + 3, q, prec);
acb_zero(thetas + 0);
/* divide the transformation factors */
Rsum = 4 * (R[1] - R[2]);
/* possible factor [q^(+/- 1/4)]^4 needed for theta_1^4 or theta_2^4 */
qpower = (S[1] == 0 || S[1] == 1) - (S[2] == 0 || S[2] == 1);
acb_div(r, thetas + S[1], thetas + S[2], prec);
acb_mul(r, r, r, prec);
acb_mul(r, r, r, prec);
if ((Rsum & 7) == 4)
acb_neg(r, r);
if (qpower == 1)
acb_mul(r, r, q, prec);
else if (qpower == -1)
acb_div(r, r, q, prec);
psl2z_clear(g);
arf_clear(one_minus_eps);
acb_clear(tau_prime);
acb_clear(q);
acb_clear(thetas + 0);
acb_clear(thetas + 1);
acb_clear(thetas + 2);
acb_clear(thetas + 3);
}
void
_acb_poly_evaluate_rectangular(acb_t y, acb_srcptr poly,
slong len, const acb_t x, slong prec)
{
slong i, j, m, r;
acb_ptr xs;
acb_t s, t, c;
if (len < 3)
{
if (len == 0)
{
acb_zero(y);
}
else if (len == 1)
{
acb_set_round(y, poly + 0, prec);
}
else if (len == 2)
{
acb_mul(y, x, poly + 1, prec);
acb_add(y, y, poly + 0, prec);
}
return;
}
m = n_sqrt(len) + 1;
r = (len + m - 1) / m;
xs = _acb_vec_init(m + 1);
acb_init(s);
acb_init(t);
acb_init(c);
_acb_vec_set_powers(xs, x, m + 1, prec);
acb_set(y, poly + (r - 1) * m);
for (j = 1; (r - 1) * m + j < len; j++)
acb_addmul(y, xs + j, poly + (r - 1) * m + j, prec);
for (i = r - 2; i >= 0; i--)
{
acb_set(s, poly + i * m);
for (j = 1; j < m; j++)
acb_addmul(s, xs + j, poly + i * m + j, prec);
acb_mul(y, y, xs + m, prec);
acb_add(y, y, s, prec);
}
_acb_vec_clear(xs, m + 1);
acb_clear(s);
acb_clear(t);
acb_clear(c);
}
void
acb_hypgeom_bessel_jy(acb_t res1, acb_t res2, const acb_t nu, const acb_t z, slong prec)
{
acb_t jnu, t, u, v;
acb_init(jnu);
acb_init(t);
acb_init(u);
acb_init(v);
acb_hypgeom_bessel_j(jnu, nu, z, prec);
if (acb_is_int(nu))
{
int is_real = acb_is_real(nu) && acb_is_real(z)
&& arb_is_positive(acb_realref(z));
acb_mul_onei(t, z);
acb_hypgeom_bessel_k(t, nu, t, prec);
acb_onei(u);
acb_pow(u, u, nu, prec);
acb_mul(t, t, u, prec);
acb_const_pi(u, prec);
acb_div(t, t, u, prec);
acb_mul_2exp_si(t, t, 1);
acb_neg(t, t);
phase(v, acb_realref(z), acb_imagref(z));
acb_mul(u, jnu, v, prec);
acb_mul_onei(u, u);
acb_sub(res2, t, u, prec);
if (is_real)
arb_zero(acb_imagref(res2));
}
else
{
acb_sin_cos_pi(t, u, nu, prec);
acb_mul(v, jnu, u, prec);
acb_neg(u, nu);
acb_hypgeom_bessel_j(u, u, z, prec);
acb_sub(v, v, u, prec);
acb_div(res2, v, t, prec);
}
if (res1 != NULL)
acb_set(res1, jnu);
acb_clear(jnu);
acb_clear(t);
acb_clear(u);
acb_clear(v);
}
void
acb_hypgeom_bessel_j_0f1(acb_t res, const acb_t nu, const acb_t z, long prec)
{
acb_struct b[2];
acb_t w, c, t;
if (acb_is_int(nu) && arb_is_negative(acb_realref(nu)))
{
acb_init(t);
acb_neg(t, nu);
acb_hypgeom_bessel_j_0f1(res, t, z, prec);
acb_mul_2exp_si(t, t, -1);
if (!acb_is_int(t))
acb_neg(res, res);
acb_clear(t);
return;
}
acb_init(b + 0);
acb_init(b + 1);
acb_init(w);
acb_init(c);
acb_init(t);
acb_add_ui(b + 0, nu, 1, prec);
acb_one(b + 1);
/* (z/2)^nu / gamma(nu+1) */
acb_mul_2exp_si(c, z, -1);
acb_pow(c, c, nu, prec);
acb_rgamma(t, b + 0, prec);
acb_mul(c, t, c, prec);
/* -z^2/4 */
acb_mul(w, z, z, prec);
acb_mul_2exp_si(w, w, -2);
acb_neg(w, w);
acb_hypgeom_pfq_direct(t, NULL, 0, b, 2, w, -1, prec);
acb_mul(res, t, c, prec);
acb_clear(b + 0);
acb_clear(b + 1);
acb_clear(w);
acb_clear(c);
acb_clear(t);
}
void acb_hypgeom_beta_lower(acb_t res,
const acb_t a, const acb_t b, const acb_t z, int regularized, slong prec)
{
acb_t t, u;
if (acb_is_zero(z) && arb_is_positive(acb_realref(a)))
{
acb_zero(res);
return;
}
if (acb_is_one(z) && arb_is_positive(acb_realref(b)))
{
if (regularized)
acb_one(res);
else
acb_beta(res, a, b, prec);
return;
}
acb_init(t);
acb_init(u);
acb_sub_ui(t, b, 1, prec);
acb_neg(t, t);
acb_add_ui(u, a, 1, prec);
if (regularized)
{
acb_hypgeom_2f1(t, a, t, u, z, 1, prec);
acb_add(u, a, b, prec);
acb_gamma(u, u, prec);
acb_mul(t, t, u, prec);
acb_rgamma(u, b, prec);
acb_mul(t, t, u, prec);
}
else
{
acb_hypgeom_2f1(t, a, t, u, z, 0, prec);
acb_div(t, t, a, prec);
}
acb_pow(u, z, a, prec);
acb_mul(t, t, u, prec);
acb_set(res, t);
acb_clear(t);
acb_clear(u);
}
void
acb_hypgeom_erf_asymp(acb_t res, const acb_t z, slong prec, slong prec2)
{
acb_t a, t, u;
acb_init(a);
acb_init(t);
acb_init(u);
acb_one(a);
acb_mul_2exp_si(a, a, -1);
acb_mul(t, z, z, prec2);
acb_hypgeom_u_asymp(u, a, a, t, -1, prec2);
acb_neg(t, t);
acb_exp(t, t, prec2);
acb_mul(u, u, t, prec2);
acb_const_pi(t, prec2);
acb_sqrt(t, t, prec2);
acb_mul(t, t, z, prec2);
acb_div(u, u, t, prec2);
/* branch cut term: -1 or 1 */
if (arb_contains_zero(acb_realref(z)))
{
arb_zero(acb_imagref(t));
arf_zero(arb_midref(acb_realref(t)));
mag_one(arb_radref(acb_realref(t)));
}
else
{
acb_set_si(t, arf_sgn(arb_midref(acb_realref(z))));
}
acb_sub(t, t, u, prec);
if (arb_is_zero(acb_imagref(z)))
arb_zero(acb_imagref(t));
else if (arb_is_zero(acb_realref(z)))
arb_zero(acb_realref(t));
acb_set(res, t);
acb_clear(a);
acb_clear(t);
acb_clear(u);
}
void
acb_hypgeom_laguerre_l_ui_recurrence(acb_t res, ulong n, const acb_t m,
const acb_t z, slong prec)
{
acb_t t, u, v;
ulong k;
if (n == 0)
{
acb_one(res);
return;
}
if (n == 1)
{
acb_sub(res, m, z, prec);
acb_add_ui(res, res, 1, prec);
return;
}
acb_init(t);
acb_init(u);
acb_init(v);
acb_one(t);
acb_sub(u, m, z, prec);
acb_add_ui(u, u, 1, prec);
for (k = 2; k <= n; k++)
{
acb_add_ui(v, m, k - 1, prec);
acb_mul(t, t, v, prec);
acb_add_ui(v, m, 2 * k - 1, prec);
acb_sub(v, v, z, prec);
acb_mul(v, v, u, prec);
acb_sub(t, v, t, prec);
acb_div_ui(t, t, k, prec);
acb_swap(t, u);
}
acb_set(res, u);
acb_clear(t);
acb_clear(u);
acb_clear(v);
}
/* res = src * (c + x) */
void _acb_poly_mullow_cpx(acb_ptr res, acb_srcptr src, slong len, const acb_t c, slong trunc, slong prec)
{
slong i;
if (len < trunc)
acb_set(res + len, src + len - 1);
for (i = len - 1; i > 0; i--)
{
acb_mul(res + i, src + i, c, prec);
acb_add(res + i, res + i, src + i - 1, prec);
}
acb_mul(res, src, c, prec);
}
void
acb_hypgeom_bessel_i_asymp_prefactors(acb_t A, acb_t B, acb_t C,
const acb_t nu, const acb_t z, long prec)
{
acb_t t, u;
acb_init(t);
acb_init(u);
/* C = (2 pi z)^(-1/2) */
acb_const_pi(C, prec);
acb_mul_2exp_si(C, C, 1);
acb_mul(C, C, z, prec);
acb_rsqrt(C, C, prec);
if (arb_is_positive(acb_imagref(z)) ||
(arb_is_zero(acb_imagref(z)) && arb_is_negative(acb_realref(z))))
{
acb_exp_pi_i(t, nu, prec);
acb_mul_onei(t, t);
}
else if (arb_is_negative(acb_imagref(z)) ||
(arb_is_zero(acb_imagref(z)) && arb_is_positive(acb_realref(z))))
{
acb_neg(t, nu);
acb_exp_pi_i(t, t, prec);
acb_mul_onei(t, t);
acb_neg(t, t);
}
else
{
acb_exp_pi_i(t, nu, prec);
acb_mul_onei(t, t);
acb_neg(u, nu);
acb_exp_pi_i(u, u, prec);
acb_mul_onei(u, u);
acb_neg(u, u);
arb_union(acb_realref(t), acb_realref(t), acb_realref(u), prec);
arb_union(acb_imagref(t), acb_imagref(t), acb_imagref(u), prec);
}
acb_exp_invexp(B, A, z, prec);
acb_mul(A, A, t, prec);
acb_clear(t);
acb_clear(u);
}
void
acb_hypgeom_laguerre_l(acb_t res, const acb_t n, const acb_t m, const acb_t z, slong prec)
{
acb_t t, u, v;
if (use_recurrence(n, m, prec))
{
acb_hypgeom_laguerre_l_ui_recurrence(res,
arf_get_si(arb_midref(acb_realref(n)), ARF_RND_DOWN), m, z, prec);
return;
}
/* todo: should be a test of whether n contains any negative integer */
if (acb_contains_int(n) && !arb_is_nonnegative(acb_realref(n)))
{
acb_indeterminate(res);
return;
}
acb_init(t);
acb_init(u);
acb_init(v);
acb_neg(t, n);
acb_add_ui(u, m, 1, prec);
acb_hypgeom_m(t, t, u, z, 1, prec);
acb_add_ui(u, n, 1, prec);
acb_rising(u, u, m, prec);
acb_mul(res, t, u, prec);
acb_clear(t);
acb_clear(u);
acb_clear(v);
}
/* f(z) = sin((1/1000 + (1-z)^2)^(-3/2)), example from Mioara Joldes' thesis
(suggested by Nicolas Brisebarre) */
int
f_sin_near_essing(acb_ptr res, const acb_t z, void * param, slong order, slong prec)
{
acb_t t, u;
if (order > 1)
flint_abort(); /* Would be needed for Taylor method. */
acb_init(t);
acb_init(u);
acb_sub_ui(t, z, 1, prec);
acb_neg(t, t);
acb_mul(t, t, t, prec);
acb_one(u);
acb_div_ui(u, u, 1000, prec);
acb_add(t, t, u, prec);
acb_set_d(u, -1.5);
acb_pow_analytic(t, t, u, order != 0, prec);
acb_sin(res, t, prec);
acb_clear(t);
acb_clear(u);
return 0;
}
int
f_horror(acb_ptr res, const acb_t z, void * param, slong order, slong prec)
{
acb_t s, t;
if (order > 1)
flint_abort(); /* Would be needed for Taylor method. */
acb_init(s);
acb_init(t);
acb_real_floor(res, z, order != 0, prec);
if (acb_is_finite(res))
{
acb_sub(res, z, res, prec);
acb_set_d(t, 0.5);
acb_sub(res, res, t, prec);
acb_sin_cos(s, t, z, prec);
acb_real_max(s, s, t, order != 0, prec);
acb_mul(res, res, s, prec);
}
acb_clear(s);
acb_clear(t);
return 0;
}
/* Differential equation for F(a,b,c,y+z):
(y+z)(y-1+z) F''(z) + ((y+z)(a+b+1) - c) F'(z) + a b F(z) = 0
Coefficients in the Taylor series are bounded by
A * binomial(N+k, k) * nu^k
using the Cauchy-Kovalevskaya majorant method.
See J. van der Hoeven, "Fast evaluation of holonomic functions near
and in regular singularities"
*/
static void
bound(mag_t A, mag_t nu, mag_t N,
const acb_t a, const acb_t b, const acb_t c, const acb_t y,
const acb_t f0, const acb_t f1)
{
mag_t M0, M1, t, u;
acb_t d;
acb_init(d);
mag_init(M0);
mag_init(M1);
mag_init(t);
mag_init(u);
/* nu = max(1/|y-1|, 1/|y|) = 1/min(|y-1|, |y|) */
acb_get_mag_lower(t, y);
acb_sub_ui(d, y, 1, MAG_BITS);
acb_get_mag_lower(u, d);
mag_min(t, t, u);
mag_one(u);
mag_div(nu, u, t);
/* M0 = 2 nu |ab| */
acb_get_mag(t, a);
acb_get_mag(u, b);
mag_mul(M0, t, u);
mag_mul(M0, M0, nu);
mag_mul_2exp_si(M0, M0, 1);
/* M1 = 2 nu |(a+b+1)y-c| + 2|a+b+1| */
acb_add(d, a, b, MAG_BITS);
acb_add_ui(d, d, 1, MAG_BITS);
acb_get_mag(t, d);
acb_mul(d, d, y, MAG_BITS);
acb_sub(d, d, c, MAG_BITS);
acb_get_mag(u, d);
mag_mul(u, u, nu);
mag_add(M1, t, u);
mag_mul_2exp_si(M1, M1, 1);
/* N = max(sqrt(2 M0), 2 M1) / nu */
mag_mul_2exp_si(M0, M0, 1);
mag_sqrt(M0, M0);
mag_mul_2exp_si(M1, M1, 1);
mag_max(N, M0, M1);
mag_div(N, N, nu);
/* A = max(|f0|, |f1| / (nu (N+1)) */
acb_get_mag(t, f0);
acb_get_mag(u, f1);
mag_div(u, u, nu);
mag_div(u, u, N); /* upper bound for dividing by N+1 */
mag_max(A, t, u);
acb_clear(d);
mag_clear(M0);
mag_clear(M1);
mag_clear(t);
mag_clear(u);
}
int
f_monster(acb_ptr res, const acb_t z, void * param, slong order, slong prec)
{
acb_t t;
if (order > 1)
flint_abort(); /* Would be needed for Taylor method. */
acb_init(t);
acb_exp(t, z, prec);
acb_real_floor(res, t, order != 0, prec);
if (acb_is_finite(res))
{
acb_sub(res, t, res, prec);
acb_add(t, t, z, prec);
acb_sin(t, t, prec);
acb_mul(res, res, t, prec);
}
acb_clear(t);
return 0;
}
static void
acb_log1p_tiny(acb_t r, const acb_t z, slong prec)
{
mag_t b, c;
acb_t t;
int real;
mag_init(b);
mag_init(c);
acb_init(t);
real = acb_is_real(z);
/* if |z| < 1, then |log(1+z) - [z - z^2/2]| <= |z|^3/(1-|z|) */
acb_get_mag(b, z);
mag_one(c);
mag_sub_lower(c, c, b);
mag_pow_ui(b, b, 3);
mag_div(b, b, c);
acb_mul(t, z, z, prec);
acb_mul_2exp_si(t, t, -1);
acb_sub(r, z, t, prec);
if (real && mag_is_finite(b))
arb_add_error_mag(acb_realref(r), b);
else
acb_add_error_mag(r, b);
mag_clear(b);
mag_clear(c);
acb_clear(t);
}
/* assumes no aliasing of w and p */
void
acb_lambertw_branchpoint_series(acb_t w, const acb_t t, int bound, slong prec)
{
slong i;
static const int coeffs[] = {-130636800,130636800,-43545600,19958400,
-10402560,5813640,-3394560,2042589,-1256320};
acb_zero(w);
for (i = 8; i >= 0; i--)
{
acb_mul(w, w, t, prec);
acb_add_si(w, w, coeffs[i], prec);
}
acb_div_si(w, w, -coeffs[0], prec);
if (bound)
{
mag_t err;
mag_init(err);
acb_get_mag(err, t);
mag_geom_series(err, err, 9);
if (acb_is_real(t))
arb_add_error_mag(acb_realref(w), err);
else
acb_add_error_mag(w, err);
mag_clear(err);
}
}
void
_acb_poly_sin_series(acb_ptr g, acb_srcptr h, slong hlen, slong n, slong prec)
{
hlen = FLINT_MIN(hlen, n);
if (hlen == 1)
{
acb_sin(g, h, prec);
_acb_vec_zero(g + 1, n - 1);
}
else if (n == 2)
{
acb_t t;
acb_init(t);
acb_sin_cos(g, t, h, prec);
acb_mul(g + 1, h + 1, t, prec); /* safe since hlen >= 2 */
acb_clear(t);
}
else
{
acb_ptr t = _acb_vec_init(n);
_acb_poly_sin_cos_series(g, t, h, hlen, n, prec);
_acb_vec_clear(t, n);
}
}
void
acb_dot_simple(acb_t res, const acb_t initial, int subtract,
acb_srcptr x, slong xstep, acb_srcptr y, slong ystep, slong len, slong prec)
{
slong i;
if (len <= 0)
{
if (initial == NULL)
acb_zero(res);
else
acb_set_round(res, initial, prec);
return;
}
if (initial == NULL)
{
acb_mul(res, x, y, prec);
}
else
{
if (subtract)
acb_neg(res, initial);
else
acb_set(res, initial);
acb_addmul(res, x, y, prec);
}
for (i = 1; i < len; i++)
acb_addmul(res, x + i * xstep, y + i * ystep, prec);
if (subtract)
acb_neg(res, res);
}
void fft(acb_t *x) {
long *base=(long *)x-2,i,j,k,l;
long n=base[0],prec=base[1],halfn=n>>1;
acb_t *p,*w=x+n;
static acb_t ctemp;
static int init;
if (!init) {
acb_init(ctemp);
init = 1;
}
/* swap each element with one with bit-reversed index */
for (i=0;i<halfn;++i) {
/* j = bit reversal of i */
for (k=1,j=0;k<n;k<<=1) {
j <<= 1;
if (i & k) j |= 1;
}
if (i < j)
acb_swap(x[i],x[j]);
else if (i > j)
acb_swap(x[n-1-i],x[n-1-j]);
++i, j |= halfn;
acb_swap(x[i],x[j]);
}
for (k=1,l=halfn;k<n;k<<=1,l>>=1)
for (p=x;p<w;p+=k)
for (j=0;j<halfn;j+=l,p++) {
acb_mul(ctemp,p[k],w[j],prec);
acb_sub(p[k],p[0],ctemp,prec);
acb_add(p[0],p[0],ctemp,prec);
}
}
