/* this can be improved */ static int use_recurrence(const acb_t n, const acb_t a, const acb_t b, slong prec) { if (!acb_is_int(n) || !arb_is_nonnegative(acb_realref(n))) return 0; if (arf_cmpabs_ui(arb_midref(acb_realref(n)), prec) > 0) return 0; if (arb_is_nonnegative(acb_realref(a)) || arf_get_d(arb_midref(acb_realref(a)), ARF_RND_DOWN) > -0.9) return 0; return 1; }
void acb_rising(acb_t y, const acb_t x, const acb_t n, long prec) { if (acb_is_int(n) && arf_sgn(arb_midref(acb_realref(n))) >= 0 && arf_cmpabs_ui(arb_midref(acb_realref(n)), FLINT_MAX(prec, 100)) < 0) { acb_rising_ui_rec(y, x, arf_get_si(arb_midref(acb_realref(n)), ARF_RND_DOWN), prec); } else { acb_t t; acb_init(t); acb_add(t, x, n, prec); acb_gamma(t, t, prec); acb_rgamma(y, x, prec); acb_mul(y, y, t, prec); acb_clear(t); } }
void _arb_poly_rgamma_series(arb_ptr res, arb_srcptr h, long hlen, long len, long prec) { int reflect; long i, rflen, r, n, wp; arb_ptr t, u, v; arb_struct f[2]; hlen = FLINT_MIN(hlen, len); wp = prec + FLINT_BIT_COUNT(prec); t = _arb_vec_init(len); u = _arb_vec_init(len); v = _arb_vec_init(len); arb_init(f); arb_init(f + 1); /* use zeta values at small integers */ if (arb_is_int(h) && (arf_cmpabs_ui(arb_midref(h), prec / 2) < 0)) { r = arf_get_si(arb_midref(h), ARF_RND_DOWN); _arb_poly_lgamma_series_at_one(u, len, wp); _arb_vec_neg(u, u, len); _arb_poly_exp_series(t, u, len, len, wp); if (r == 1) { _arb_vec_swap(v, t, len); } else if (r <= 0) { arb_set(f, h); arb_one(f + 1); rflen = FLINT_MIN(len, 2 - r); _arb_poly_rising_ui_series(u, f, FLINT_MIN(2, len), 1 - r, rflen, wp); _arb_poly_mullow(v, t, len, u, rflen, len, wp); } else { arb_one(f); arb_one(f + 1); rflen = FLINT_MIN(len, r); _arb_poly_rising_ui_series(v, f, FLINT_MIN(2, len), r - 1, rflen, wp); /* TODO: use div_series? */ _arb_poly_inv_series(u, v, rflen, len, wp); _arb_poly_mullow(v, t, len, u, len, len, wp); } } else { /* otherwise use Stirling series */ arb_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) */ arb_sub_ui(f, h, r + 1, wp); arb_neg(f, f); _arb_poly_gamma_stirling_eval(t, f, n, len, wp); _arb_poly_exp_series(u, t, len, len, wp); for (i = 1; i < len; i += 2) arb_neg(u + i, u + i); /* v = sin(pi x) */ arb_const_pi(f + 1, wp); arb_mul(f, h, f + 1, wp); _arb_poly_sin_series(v, f, 2, len, wp); _arb_poly_mullow(t, u, len, v, len, len, wp); /* rf(1-h,r) * pi */ if (r == 0) { arb_const_pi(u, wp); _arb_vec_scalar_div(v, t, len, u, wp); } else { arb_sub_ui(f, h, 1, wp); arb_neg(f, f); arb_set_si(f + 1, -1); rflen = FLINT_MIN(len, r + 1); _arb_poly_rising_ui_series(v, f, FLINT_MIN(2, len), r, rflen, wp); arb_const_pi(u, wp); _arb_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 */ _arb_poly_inv_series(u, v, rflen, len, wp); _arb_poly_mullow(v, t, len, u, len, len, wp); } } else { /* rgamma(h) = rgamma(h+r) rf(h,r) */ if (r == 0) { arb_add_ui(f, h, r, wp); _arb_poly_gamma_stirling_eval(t, f, n, len, wp); _arb_vec_neg(t, t, len); _arb_poly_exp_series(v, t, len, len, wp); } else { arb_set(f, h); arb_one(f + 1); rflen = FLINT_MIN(len, r + 1); _arb_poly_rising_ui_series(t, f, FLINT_MIN(2, len), r, rflen, wp); arb_add_ui(f, h, r, wp); _arb_poly_gamma_stirling_eval(v, f, n, len, wp); _arb_vec_neg(v, v, len); _arb_poly_exp_series(u, v, len, len, wp); _arb_poly_mullow(v, u, len, t, rflen, len, wp); } } } /* compose with nonconstant part */ arb_zero(t); _arb_vec_set(t + 1, h + 1, hlen - 1); _arb_poly_compose_series(res, v, len, t, hlen, len, prec); arb_clear(f); arb_clear(f + 1); _arb_vec_clear(t, len); _arb_vec_clear(u, len); _arb_vec_clear(v, len); }
/* derivatives: |8/sqrt(pi) sin(2z^2)|, |8/sqrt(pi) cos(2z^2)| <= 5 exp(4|xy|) */ void acb_hypgeom_fresnel_erf_error(acb_t res1, acb_t res2, const acb_t z, slong prec) { mag_t re; mag_t im; acb_t zmid; mag_init(re); mag_init(im); acb_init(zmid); if (arf_cmpabs_ui(arb_midref(acb_realref(z)), 1000) < 0 && arf_cmpabs_ui(arb_midref(acb_imagref(z)), 1000) < 0) { arb_get_mag(re, acb_realref(z)); arb_get_mag(im, acb_imagref(z)); mag_mul(re, re, im); mag_mul_2exp_si(re, re, 2); mag_exp(re, re); mag_mul_ui(re, re, 5); } else { arb_t t; arb_init(t); arb_mul(t, acb_realref(z), acb_imagref(z), prec); arb_abs(t, t); arb_mul_2exp_si(t, t, 2); arb_exp(t, t, prec); arb_get_mag(re, t); mag_mul_ui(re, re, 5); arb_clear(t); } mag_hypot(im, arb_radref(acb_realref(z)), arb_radref(acb_imagref(z))); mag_mul(re, re, im); if (arb_is_zero(acb_imagref(z))) { mag_set_ui(im, 8); /* For real x, |S(x)| < 4, |C(x)| < 4. */ mag_min(re, re, im); mag_zero(im); } else if (arb_is_zero(acb_realref(z))) { mag_set_ui(im, 8); mag_min(im, re, im); mag_zero(re); } else { mag_set(im, re); } arf_set(arb_midref(acb_realref(zmid)), arb_midref(acb_realref(z))); arf_set(arb_midref(acb_imagref(zmid)), arb_midref(acb_imagref(z))); acb_hypgeom_fresnel_erf(res1, res2, zmid, prec); if (res1 != NULL) { arb_add_error_mag(acb_realref(res1), re); arb_add_error_mag(acb_imagref(res1), im); } if (res2 != NULL) { arb_add_error_mag(acb_realref(res2), re); arb_add_error_mag(acb_imagref(res2), im); } mag_clear(re); mag_clear(im); acb_clear(zmid); }
void acb_hypgeom_erf_asymp(acb_t res, const acb_t z, int complementary, slong prec, slong prec2) { acb_t a, t, u; acb_init(a); acb_init(t); acb_init(u); if (!acb_is_exact(z) && (arf_cmpabs_ui(arb_midref(acb_realref(z)), prec) < 0) && (arf_cmpabs_ui(arb_midref(acb_imagref(z)), prec) < 0)) { acb_t zmid; mag_t re_err, im_err; acb_init(zmid); mag_init(re_err); mag_init(im_err); acb_hypgeom_erf_propagated_error(re_err, im_err, z); arf_set(arb_midref(acb_realref(zmid)), arb_midref(acb_realref(z))); arf_set(arb_midref(acb_imagref(zmid)), arb_midref(acb_imagref(z))); acb_hypgeom_erf_asymp(res, zmid, complementary, prec, prec2); arb_add_error_mag(acb_realref(res), re_err); arb_add_error_mag(acb_imagref(res), im_err); acb_clear(zmid); mag_clear(re_err); mag_clear(im_err); return; } 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); arb_const_sqrt_pi(acb_realref(t), prec2); arb_zero(acb_imagref(t)); acb_mul(t, t, z, prec2); acb_div(u, u, t, prec2); /* branch cut term: -1 or 1 */ acb_csgn(acb_realref(t), z); arb_zero(acb_imagref(t)); if (complementary) { /* erfc(z) = 1 - erf(z) = u - (sgn - 1) */ acb_sub_ui(t, t, 1, prec); acb_sub(t, u, t, prec); } else { /* erf(z) = sgn - u */ 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))) { if (complementary) arb_one(acb_realref(t)); else arb_zero(acb_realref(t)); } acb_set(res, t); acb_clear(a); acb_clear(t); acb_clear(u); }
void acb_hypgeom_2f1(acb_t res, const acb_t a, const acb_t b, const acb_t c, const acb_t z, int flags, slong prec) { int algorithm, regularized; regularized = flags & ACB_HYPGEOM_2F1_REGULARIZED; if (!acb_is_finite(a) || !acb_is_finite(b) || !acb_is_finite(c) || !acb_is_finite(z)) { acb_indeterminate(res); return; } if (acb_is_zero(z)) { if (regularized) acb_rgamma(res, c, prec); else acb_one(res); return; } if (regularized && acb_is_int(c) && arb_is_nonpositive(acb_realref(c))) { if ((acb_is_int(a) && arb_is_nonpositive(acb_realref(a)) && arf_cmp(arb_midref(acb_realref(a)), arb_midref(acb_realref(c))) >= 0) || (acb_is_int(b) && arb_is_nonpositive(acb_realref(b)) && arf_cmp(arb_midref(acb_realref(b)), arb_midref(acb_realref(c))) >= 0)) { acb_zero(res); return; } } if (regularized && acb_eq(a, c)) { _acb_hypgeom_2f1r_reduced(res, b, c, z, prec); return; } if (regularized && acb_eq(b, c)) { _acb_hypgeom_2f1r_reduced(res, a, c, z, prec); return; } /* polynomial */ if (acb_is_int(a) && arf_sgn(arb_midref(acb_realref(a))) <= 0 && arf_cmpabs_ui(arb_midref(acb_realref(a)), prec) < 0) { acb_hypgeom_2f1_direct(res, a, b, c, z, regularized, prec); return; } /* polynomial */ if (acb_is_int(b) && arf_sgn(arb_midref(acb_realref(b))) <= 0 && arf_cmpabs_ui(arb_midref(acb_realref(b)), prec) < 0) { acb_hypgeom_2f1_direct(res, a, b, c, z, regularized, prec); return; } /* Try to reduce to a polynomial case using the Pfaff transformation */ /* TODO: look at flags for integer c-b, c-a here, even when c is nonexact */ if (acb_is_exact(c)) { acb_t t; acb_init(t); acb_sub(t, c, b, prec); if (acb_is_int(t) && arb_is_nonpositive(acb_realref(t))) { acb_hypgeom_2f1_transform(res, a, b, c, z, flags, 1, prec); acb_clear(t); return; } acb_sub(t, c, a, prec); if (acb_is_int(t) && arb_is_nonpositive(acb_realref(t))) { int f1, f2; /* When swapping a, b, also swap the flags. */ f1 = flags & ACB_HYPGEOM_2F1_AC; f2 = flags & ACB_HYPGEOM_2F1_BC; flags &= ~ACB_HYPGEOM_2F1_AC; flags &= ~ACB_HYPGEOM_2F1_BC; if (f1) flags |= ACB_HYPGEOM_2F1_BC; if (f2) flags |= ACB_HYPGEOM_2F1_AC; acb_hypgeom_2f1_transform(res, b, a, c, z, flags, 1, prec); acb_clear(t); return; } acb_clear(t); } /* special value at z = 1 */ if (acb_is_one(z)) { acb_t t, u, v; acb_init(t); acb_init(u); acb_init(v); acb_sub(t, c, a, prec); acb_sub(u, c, b, prec); acb_sub(v, t, b, prec); if (arb_is_positive(acb_realref(v))) { acb_rgamma(t, t, prec); acb_rgamma(u, u, prec); acb_mul(t, t, u, prec); acb_gamma(v, v, prec); acb_mul(t, t, v, prec); if (!regularized) { acb_gamma(v, c, prec); acb_mul(t, t, v, prec); } acb_set(res, t); } else { acb_indeterminate(res); } acb_clear(t); acb_clear(u); acb_clear(v); return; } algorithm = acb_hypgeom_2f1_choose(z); if (algorithm == 0) { acb_hypgeom_2f1_direct(res, a, b, c, z, regularized, prec); } else if (algorithm >= 1 && algorithm <= 5) { acb_hypgeom_2f1_transform(res, a, b, c, z, flags, algorithm, prec); } else { acb_hypgeom_2f1_corner(res, a, b, c, z, regularized, prec); } }
void _arb_poly_lgamma_series(arb_ptr res, arb_srcptr h, slong hlen, slong len, slong prec) { int reflect; slong r, n, wp; arb_t zr; arb_ptr t, u; if (!arb_is_positive(h)) { _arb_vec_indeterminate(res, len); return; } hlen = FLINT_MIN(hlen, len); wp = prec + FLINT_BIT_COUNT(prec); t = _arb_vec_init(len); u = _arb_vec_init(len); arb_init(zr); /* use zeta values at small integers */ if (arb_is_int(h) && (arf_cmpabs_ui(arb_midref(h), prec / 2) < 0)) { r = arf_get_si(arb_midref(h), ARF_RND_DOWN); if (r <= 0) { _arb_vec_indeterminate(res, len); goto cleanup; } else { _arb_poly_lgamma_series_at_one(u, len, wp); if (r != 1) { arb_one(zr); _log_rising_ui_series(t, zr, r - 1, len, wp); _arb_vec_add(u, u, t, len, wp); } } } else if (len <= 2) { arb_lgamma(u, h, wp); if (len == 2) arb_digamma(u + 1, h, wp); } else { /* otherwise use Stirling series */ arb_gamma_stirling_choose_param(&reflect, &r, &n, h, 0, 0, wp); arb_add_ui(zr, h, r, wp); _arb_poly_gamma_stirling_eval(u, zr, n, len, wp); if (r != 0) { _log_rising_ui_series(t, h, r, len, wp); _arb_vec_sub(u, u, t, len, wp); } } /* compose with nonconstant part */ arb_zero(t); _arb_vec_set(t + 1, h + 1, hlen - 1); _arb_poly_compose_series(res, u, len, t, hlen, len, prec); cleanup: arb_clear(zr); _arb_vec_clear(t, len); _arb_vec_clear(u, len); }
void acb_hypgeom_u_asymp(acb_t res, const acb_t a, const acb_t b, const acb_t z, slong n, slong prec) { acb_struct aa[3]; acb_t s, t, w, winv; int R, p, q, is_real, is_terminating; slong n_terminating; if (!acb_is_finite(a) || !acb_is_finite(b) || !acb_is_finite(z)) { acb_indeterminate(res); return; } acb_init(aa); acb_init(aa + 1); acb_init(aa + 2); acb_init(s); acb_init(t); acb_init(w); acb_init(winv); is_terminating = 0; n_terminating = WORD_MAX; /* special case, for incomplete gamma [todo: also when they happen to be exact and with difference 1...] */ if (a == b) { acb_set(aa, a); p = 1; q = 0; } else { acb_set(aa, a); acb_sub(aa + 1, a, b, prec); acb_add_ui(aa + 1, aa + 1, 1, prec); acb_one(aa + 2); p = 2; q = 1; } if (acb_is_nonpositive_int(aa)) { is_terminating = 1; if (arf_cmpabs_ui(arb_midref(acb_realref(aa)), prec) < 0) n_terminating = 1 - arf_get_si(arb_midref(acb_realref(aa)), ARF_RND_DOWN); } if (p == 2 && acb_is_nonpositive_int(aa + 1)) { is_terminating = 1; if (arf_cmpabs_ui(arb_midref(acb_realref(aa + 1)), n_terminating) < 0) n_terminating = 1 - arf_get_si(arb_midref(acb_realref(aa + 1)), ARF_RND_DOWN); } acb_neg(w, z); acb_inv(w, w, prec); acb_neg(winv, z); /* low degree polynomial -- no need to try to terminate sooner */ if (is_terminating && n_terminating < 8) { acb_hypgeom_pfq_sum_invz(s, t, aa, p, aa + p, q, w, winv, n_terminating, prec); acb_set(res, s); } else { mag_t C1, Cn, alpha, nu, sigma, rho, zinv, tmp, err; mag_init(C1); mag_init(Cn); mag_init(alpha); mag_init(nu); mag_init(sigma); mag_init(rho); mag_init(zinv); mag_init(tmp); mag_init(err); acb_hypgeom_u_asymp_bound_factors(&R, alpha, nu, sigma, rho, zinv, a, b, z); is_real = acb_is_real(a) && acb_is_real(b) && acb_is_real(z) && (is_terminating || arb_is_positive(acb_realref(z))); if (R == 0) { /* if R == 0, the error bound is infinite unless terminating */ if (is_terminating && n_terminating < prec) { acb_hypgeom_pfq_sum_invz(s, t, aa, p, aa + p, q, w, winv, n_terminating, prec); acb_set(res, s); } else { acb_indeterminate(res); } } else { /* C1 */ acb_hypgeom_mag_Cn(C1, R, nu, sigma, 1); /* err = 2 * alpha * exp(...) */ mag_mul(tmp, C1, rho); mag_mul(tmp, tmp, alpha); mag_mul(tmp, tmp, zinv); mag_mul_2exp_si(tmp, tmp, 1); mag_exp(err, tmp); mag_mul(err, err, alpha); mag_mul_2exp_si(err, err, 1); /* choose n automatically */ if (n < 0) { slong moreprec; /* take err into account when finding truncation point */ /* we should take Cn into account as well, but this depends on n which is to be determined; it's easier to look only at exp(...) which should be larger anyway */ if (mag_cmp_2exp_si(err, 10 * prec) > 0) moreprec = 10 * prec; else if (mag_cmp_2exp_si(err, 0) < 0) moreprec = 0; else moreprec = MAG_EXP(err); n = acb_hypgeom_pfq_choose_n_max(aa, p, aa + p, q, w, prec + moreprec, FLINT_MIN(WORD_MAX / 2, 50 + 10.0 * prec)); } acb_hypgeom_pfq_sum_invz(s, t, aa, p, aa + p, q, w, winv, n, prec); /* add error bound, if not terminating */ if (!(is_terminating && n == n_terminating)) { acb_hypgeom_mag_Cn(Cn, R, nu, sigma, n); mag_mul(err, err, Cn); /* nth term * factor */ acb_get_mag(tmp, t); mag_mul(err, err, tmp); if (is_real) arb_add_error_mag(acb_realref(s), err); else acb_add_error_mag(s, err); } acb_set(res, s); } mag_clear(C1); mag_clear(Cn); mag_clear(alpha); mag_clear(nu); mag_clear(sigma); mag_clear(rho); mag_clear(zinv); mag_clear(tmp); mag_clear(err); } acb_clear(aa); acb_clear(aa + 1); acb_clear(aa + 2); acb_clear(s); acb_clear(t); acb_clear(w); acb_clear(winv); }
void acb_hypgeom_pfq_series_direct(acb_poly_t res, const acb_poly_struct * a, long p, const acb_poly_struct * b, long q, const acb_poly_t z, int regularized, long n, long len, long prec) { acb_poly_t s, t, err; arb_poly_t C, T; long i; int is_real; int terminating; /* default algorithm to choose number of terms */ if (n < 0) { n = acb_hypgeom_pfq_series_choose_n(a, p, b, q, z, len, prec); } terminating = 0; /* check if it terminates due to a root of the numerator */ for (i = 0; i < p; i++) { if (acb_poly_length(a + i) == 0 && n > 0) { terminating = 1; } else if (acb_poly_length(a + i) == 1) { acb_srcptr c = acb_poly_get_coeff_ptr(a + i, 0); if (acb_is_int(c) && arb_is_negative(acb_realref(c)) && arf_cmpabs_ui(arb_midref(acb_realref(c)), n) < 0) { terminating = 1; } } } /* check if it terminates (to order n) due to z */ /* the following tests could be made stronger... */ if (z->length == 0 && n >= 1) { terminating = 1; } else if (!terminating && z->length > 0 && acb_is_zero(z->coeffs) && n >= len) { if (regularized) { terminating = 1; } else { terminating = 1; for (i = 0; i < q; i++) { acb_srcptr c = acb_poly_get_coeff_ptr(b + i, 0); if (!arb_is_positive(acb_realref(c)) && acb_contains_int(c)) terminating = 0; } } } acb_poly_init(s); acb_poly_init(t); acb_poly_init(err); arb_poly_init(C); arb_poly_init(T); acb_hypgeom_pfq_series_sum_forward(s, t, a, p, b, q, z, regularized, n, len, prec); if (!terminating) { is_real = acb_poly_is_real(z); for (i = 0; i < p; i++) is_real = is_real && acb_poly_is_real(a + i); for (i = 0; i < q; i++) is_real = is_real && acb_poly_is_real(b + i); acb_poly_majorant(T, t, MAG_BITS); acb_hypgeom_pfq_series_bound_factor(C, a, p, b, q, z, n, len, MAG_BITS); if (!_arb_vec_is_finite(T->coeffs, T->length) || !_arb_vec_is_finite(C->coeffs, C->length)) { arb_poly_fit_length(T, len); _arb_vec_indeterminate(T->coeffs, len); _arb_poly_set_length(T, len); } else { arb_poly_mullow(T, T, C, len, MAG_BITS); } /* create polynomial of errors */ acb_poly_fit_length(err, len); for (i = 0; i < FLINT_MIN(len, T->length); i++) { arb_add_error(acb_realref(err->coeffs + i), T->coeffs + i); if (!is_real) arb_add_error(acb_imagref(err->coeffs + i), T->coeffs + i); } _acb_poly_set_length(err, len); _acb_poly_normalise(err); acb_poly_add(s, s, err, prec); } acb_poly_set(res, s); acb_poly_clear(s); acb_poly_clear(t); acb_poly_clear(err); arb_poly_clear(C); arb_poly_clear(T); }