void _acb_poly_rgamma_series(acb_ptr res, acb_srcptr h, slong hlen, slong len, slong prec) { int reflect; slong i, rflen, r, n, wp; acb_ptr t, u, v; acb_struct f[2]; hlen = FLINT_MIN(hlen, len); if (hlen == 1) { acb_rgamma(res, h, prec); _acb_vec_zero(res + 1, len - 1); return; } /* use real code for real input */ if (_acb_vec_is_real(h, hlen)) { arb_ptr tmp = _arb_vec_init(len); for (i = 0; i < hlen; i++) arb_set(tmp + i, acb_realref(h + i)); _arb_poly_rgamma_series(tmp, tmp, hlen, len, prec); for (i = 0; i < len; i++) acb_set_arb(res + i, tmp + i); _arb_vec_clear(tmp, len); return; } wp = prec + FLINT_BIT_COUNT(prec); t = _acb_vec_init(len); u = _acb_vec_init(len); v = _acb_vec_init(len); acb_init(f); acb_init(f + 1); /* otherwise use Stirling series */ acb_gamma_stirling_choose_param(&reflect, &r, &n, h, 1, 0, wp); /* rgamma(h) = (gamma(1-h+r) sin(pi h)) / (rf(1-h, r) * pi), h = h0 + t*/ if (reflect) { /* u = gamma(r+1-h) */ acb_sub_ui(f, h, r + 1, wp); acb_neg(f, f); _acb_poly_gamma_stirling_eval(t, f, n, len, wp); _acb_poly_exp_series(u, t, len, len, wp); for (i = 1; i < len; i += 2) acb_neg(u + i, u + i); /* v = sin(pi x) */ acb_set(f, h); acb_one(f + 1); _acb_poly_sin_pi_series(v, f, 2, len, wp); _acb_poly_mullow(t, u, len, v, len, len, wp); /* rf(1-h,r) * pi */ if (r == 0) { acb_const_pi(u, wp); _acb_vec_scalar_div(v, t, len, u, wp); } else { acb_sub_ui(f, h, 1, wp); acb_neg(f, f); acb_set_si(f + 1, -1); rflen = FLINT_MIN(len, r + 1); _acb_poly_rising_ui_series(v, f, FLINT_MIN(2, len), r, rflen, wp); acb_const_pi(u, wp); _acb_vec_scalar_mul(v, v, rflen, u, wp); /* divide by rising factorial */ /* TODO: might better to use div_series, when it has a good basecase */ _acb_poly_inv_series(u, v, rflen, len, wp); _acb_poly_mullow(v, t, len, u, len, len, wp); } } else { /* rgamma(h) = rgamma(h+r) rf(h,r) */ if (r == 0) { acb_add_ui(f, h, r, wp); _acb_poly_gamma_stirling_eval(t, f, n, len, wp); _acb_vec_neg(t, t, len); _acb_poly_exp_series(v, t, len, len, wp); } else { acb_set(f, h); acb_one(f + 1); rflen = FLINT_MIN(len, r + 1); _acb_poly_rising_ui_series(t, f, FLINT_MIN(2, len), r, rflen, wp); acb_add_ui(f, h, r, wp); _acb_poly_gamma_stirling_eval(v, f, n, len, wp); _acb_vec_neg(v, v, len); _acb_poly_exp_series(u, v, len, len, wp); _acb_poly_mullow(v, u, len, t, rflen, len, wp); } } /* compose with nonconstant part */ acb_zero(t); _acb_vec_set(t + 1, h + 1, hlen - 1); _acb_poly_compose_series(res, v, len, t, hlen, len, prec); acb_clear(f); acb_clear(f + 1); _acb_vec_clear(t, len); _acb_vec_clear(u, len); _acb_vec_clear(v, len); }
void acb_hypgeom_pfq_sum_rs(acb_t res, acb_t term, acb_srcptr a, slong p, acb_srcptr b, slong q, const acb_t z, slong n, slong prec) { acb_ptr zpow; acb_t s, t, u; slong i, j, k, m; mag_t B, C; if (n == 0) { acb_zero(res); acb_one(term); return; } if (n < 0) abort(); m = n_sqrt(n); m = FLINT_MIN(m, 150); mag_init(B); mag_init(C); acb_init(s); acb_init(t); acb_init(u); zpow = _acb_vec_init(m + 1); _acb_vec_set_powers(zpow, z, m + 1, prec); mag_one(B); for (k = n; k >= 0; k--) { j = k % m; if (k < n) acb_add(s, s, zpow + j, prec); if (k > 0) { if (p > 0) { acb_add_ui(u, a, k - 1, prec); for (i = 1; i < p; i++) { acb_add_ui(t, a + i, k - 1, prec); acb_mul(u, u, t, prec); } if (k < n) acb_mul(s, s, u, prec); acb_get_mag(C, u); mag_mul(B, B, C); } if (q > 0) { acb_add_ui(u, b, k - 1, prec); for (i = 1; i < q; i++) { acb_add_ui(t, b + i, k - 1, prec); acb_mul(u, u, t, prec); } if (k < n) acb_div(s, s, u, prec); acb_get_mag_lower(C, u); mag_div(B, B, C); } if (j == 0 && k < n) { acb_mul(s, s, zpow + m, prec); } } } acb_get_mag(C, z); mag_pow_ui(C, C, n); mag_mul(B, B, C); acb_zero(term); if (_acb_vec_is_real(a, p) && _acb_vec_is_real(b, q) && acb_is_real(z)) arb_add_error_mag(acb_realref(term), B); else acb_add_error_mag(term, B); acb_set(res, s); mag_clear(B); mag_clear(C); acb_clear(s); acb_clear(t); acb_clear(u); _acb_vec_clear(zpow, m + 1); }
void _acb_poly_lgamma_series(acb_ptr res, acb_srcptr h, slong hlen, slong len, slong prec) { int reflect; slong i, r, n, wp; acb_t zr; acb_ptr t, u; hlen = FLINT_MIN(hlen, len); if (hlen == 1) { acb_lgamma(res, h, prec); if (acb_is_finite(res)) _acb_vec_zero(res + 1, len - 1); else _acb_vec_indeterminate(res + 1, len - 1); return; } if (len == 2) { acb_t v; acb_init(v); acb_set(v, h + 1); acb_digamma(res + 1, h, prec); acb_lgamma(res, h, prec); acb_mul(res + 1, res + 1, v, prec); acb_clear(v); return; } /* use real code for real input and output */ if (_acb_vec_is_real(h, hlen) && arb_is_positive(acb_realref(h))) { arb_ptr tmp = _arb_vec_init(len); for (i = 0; i < hlen; i++) arb_set(tmp + i, acb_realref(h + i)); _arb_poly_lgamma_series(tmp, tmp, hlen, len, prec); for (i = 0; i < len; i++) acb_set_arb(res + i, tmp + i); _arb_vec_clear(tmp, len); return; } wp = prec + FLINT_BIT_COUNT(prec); t = _acb_vec_init(len); u = _acb_vec_init(len); acb_init(zr); /* use Stirling series */ acb_gamma_stirling_choose_param(&reflect, &r, &n, h, 1, 0, wp); if (reflect) { /* log gamma(h+x) = log rf(1-(h+x), r) - log gamma(1-(h+x)+r) - log sin(pi (h+x)) + log(pi) */ if (r != 0) /* otherwise t = 0 */ { acb_sub_ui(u, h, 1, wp); acb_neg(u, u); _log_rising_ui_series(t, u, r, len, wp); for (i = 1; i < len; i += 2) acb_neg(t + i, t + i); } acb_sub_ui(u, h, 1, wp); acb_neg(u, u); acb_add_ui(zr, u, r, wp); _acb_poly_gamma_stirling_eval(u, zr, n, len, wp); for (i = 1; i < len; i += 2) acb_neg(u + i, u + i); _acb_vec_sub(t, t, u, len, wp); /* log(sin) is unstable with large imaginary parts; cot_pi is implemented in a numerically stable way */ acb_set(u, h); acb_one(u + 1); _acb_poly_cot_pi_series(u, u, 2, len - 1, wp); _acb_poly_integral(u, u, len, wp); acb_const_pi(u, wp); _acb_vec_scalar_mul(u + 1, u + 1, len - 1, u, wp); acb_log_sin_pi(u, h, wp); _acb_vec_sub(u, t, u, len, wp); acb_const_pi(t, wp); /* todo: constant for log pi */ acb_log(t, t, wp); acb_add(u, u, t, wp); } else { /* log gamma(x) = log gamma(x+r) - log rf(x,r) */ acb_add_ui(zr, h, r, wp); _acb_poly_gamma_stirling_eval(u, zr, n, len, wp); if (r != 0) { _log_rising_ui_series(t, h, r, len, wp); _acb_vec_sub(u, u, t, len, wp); } } /* compose with nonconstant part */ acb_zero(t); _acb_vec_set(t + 1, h + 1, hlen - 1); _acb_poly_compose_series(res, u, len, t, hlen, len, prec); acb_clear(zr); _acb_vec_clear(t, len); _acb_vec_clear(u, len); }
void _acb_poly_digamma_series(acb_ptr res, acb_srcptr h, slong hlen, slong len, slong prec) { int reflect; slong i, r, n, rflen, wp; acb_t zr; acb_ptr t, u, v; hlen = FLINT_MIN(hlen, len); if (hlen == 1) { acb_digamma(res, h, prec); if (acb_is_finite(res)) _acb_vec_zero(res + 1, len - 1); else _acb_vec_indeterminate(res + 1, len - 1); return; } /* use real code for real input */ if (_acb_vec_is_real(h, hlen)) { arb_ptr tmp = _arb_vec_init(len); for (i = 0; i < hlen; i++) arb_set(tmp + i, acb_realref(h + i)); _arb_poly_digamma_series(tmp, tmp, hlen, len, prec); for (i = 0; i < len; i++) acb_set_arb(res + i, tmp + i); _arb_vec_clear(tmp, len); return; } wp = prec + FLINT_BIT_COUNT(prec); t = _acb_vec_init(len + 1); u = _acb_vec_init(len + 1); v = _acb_vec_init(len + 1); acb_init(zr); /* use Stirling series */ acb_gamma_stirling_choose_param(&reflect, &r, &n, h, 1, 1, wp); /* psi(x) = psi((1-x)+r) - h(1-x,r) - pi*cot(pi*x) */ if (reflect) { if (r != 0) /* otherwise t = 0 */ { acb_sub_ui(v, h, 1, wp); acb_neg(v, v); acb_one(v + 1); rflen = FLINT_MIN(len + 1, r + 1); _acb_poly_rising_ui_series(u, v, 2, r, rflen, wp); _acb_poly_derivative(v, u, rflen, wp); _acb_poly_div_series(t, v, rflen - 1, u, rflen, len, wp); for (i = 1; i < len; i += 2) acb_neg(t + i, t + i); } acb_sub_ui(zr, h, r + 1, wp); acb_neg(zr, zr); _acb_poly_gamma_stirling_eval2(u, zr, n, len + 1, 1, wp); for (i = 1; i < len; i += 2) acb_neg(u + i, u + i); _acb_vec_sub(u, u, t, len, wp); acb_set(t, h); acb_one(t + 1); _acb_poly_cot_pi_series(t, t, 2, len, wp); acb_const_pi(v, wp); _acb_vec_scalar_mul(t, t, len, v, wp); _acb_vec_sub(u, u, t, len, wp); } else { if (r == 0) { acb_add_ui(zr, h, r, wp); _acb_poly_gamma_stirling_eval2(u, zr, n, len + 1, 1, wp); } else { acb_set(v, h); acb_one(v + 1); rflen = FLINT_MIN(len + 1, r + 1); _acb_poly_rising_ui_series(u, v, 2, r, rflen, wp); _acb_poly_derivative(v, u, rflen, wp); _acb_poly_div_series(t, v, rflen - 1, u, rflen, len, wp); acb_add_ui(zr, h, r, wp); _acb_poly_gamma_stirling_eval2(u, zr, n, len + 1, 1, wp); _acb_vec_sub(u, u, t, len, wp); } } /* compose with nonconstant part */ acb_zero(t); _acb_vec_set(t + 1, h + 1, hlen - 1); _acb_poly_compose_series(res, u, len, t, hlen, len, prec); acb_clear(zr); _acb_vec_clear(t, len + 1); _acb_vec_clear(u, len + 1); _acb_vec_clear(v, len + 1); }