Exemplo n.º 1
0
Arquivo: log1p.c Projeto: isuruf/arb
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);
}
Exemplo n.º 2
0
/* 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);
    }
}
Exemplo n.º 3
0
int main()
{
    slong iter;
    flint_rand_t state;

    flint_printf("get_mag....");
    fflush(stdout);
    flint_randinit(state);

    for (iter = 0; iter < 10000 * arb_test_multiplier(); iter++)
    {
        acb_t a;
        arf_t m2, x, y, s;
        mag_t m;

        acb_init(a);
        mag_init(m);
        arf_init(m2);
        arf_init(x);
        arf_init(y);
        arf_init(s);

        acb_randtest_special(a, state, 200, 10);
        acb_get_mag(m, a);
        MAG_CHECK_BITS(m)

        /* check m^2 >= x^2 + y^2 */
        arf_set_mag(m2, m);
        arf_mul(m2, m2, m2, ARF_PREC_EXACT, ARF_RND_DOWN);

        arb_get_abs_ubound_arf(x, acb_realref(a), ARF_PREC_EXACT);
        arb_get_abs_ubound_arf(y, acb_imagref(a), ARF_PREC_EXACT);
        arf_sosq(s, x, y, ARF_PREC_EXACT, ARF_RND_DOWN);

        if (arf_cmp(m2, s) < 0)
        {
            flint_printf("FAIL:\n\n");
            flint_printf("a = "); acb_print(a); flint_printf("\n\n");
            flint_printf("m = "); mag_print(m); flint_printf("\n\n");
            flint_abort();
        }

        acb_clear(a);
        mag_clear(m);
        arf_clear(m2);
        arf_clear(x);
        arf_clear(y);
        arf_clear(s);
    }

    flint_randclear(state);
    flint_cleanup();
    flint_printf("PASS\n");
    return EXIT_SUCCESS;
}
Exemplo n.º 4
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);
}
Exemplo n.º 5
0
void
acb_hypgeom_bessel_k(acb_t res, const acb_t nu, const acb_t z, slong prec)
{
    mag_t zmag;

    mag_init(zmag);
    acb_get_mag(zmag, z);

    if (mag_cmp_2exp_si(zmag, 4) < 0 ||
        (mag_cmp_2exp_si(zmag, 64) < 0 && 2 * mag_get_d(zmag) < prec))
        acb_hypgeom_bessel_k_0f1(res, nu, z, prec);
    else
        acb_hypgeom_bessel_k_asymp(res, nu, z, prec);

    mag_clear(zmag);
}
Exemplo n.º 6
0
void
acb_modular_theta_const_sum(acb_t theta2, acb_t theta3, acb_t theta4,
    const acb_t q, long prec)
{
    mag_t qmag, err;
    double log2q_approx;
    int is_real, is_real_or_imag;
    long N;

    mag_init(qmag);
    mag_init(err);

    acb_get_mag(qmag, q);
    log2q_approx = mag_get_log2_d_approx(qmag);

    is_real = arb_is_zero(acb_imagref(q));
    is_real_or_imag = is_real || arb_is_zero(acb_realref(q));

    if (log2q_approx >= 0.0)
    {
        N = 1;
        mag_inf(err);
    }
    else
    {
        N = 0;

        while (0.05 * N * N < prec)
        {
            if (log2q_approx * ((N+2)*(N+2)/4) < -prec - 2)
                break;
            N++;
        }
        N = (N+2)*(N+2)/4;

        mag_geom_series(err, qmag, N);
        mag_mul_2exp_si(err, err, 1); /* each term is taken twice */

        if (mag_is_inf(err))
            N = 1;
    }

    if (N < 1800)
        acb_modular_theta_const_sum_basecase(theta2, theta3, theta4, q, N, prec);
    else
        acb_modular_theta_const_sum_rs(theta2, theta3, theta4, q, N, prec);

    if (is_real_or_imag)
        arb_add_error_mag(acb_realref(theta2), err);
    else
        acb_add_error_mag(theta2, err);

    if (is_real)
    {
        arb_add_error_mag(acb_realref(theta3), err);
        arb_add_error_mag(acb_realref(theta4), err);
    }
    else
    {
        acb_add_error_mag(theta3, err);
        acb_add_error_mag(theta4, err);
    }

    mag_clear(qmag);
    mag_clear(err);
}
Exemplo n.º 7
0
void
acb_modular_theta_const_sum_basecase(acb_t theta2, acb_t theta3, acb_t theta4,
    const acb_t q, slong N, slong prec)
{
    slong * tab;
    slong k, term_prec;
    double log2q_approx, log2term_approx;
    mag_t qmag;
    acb_ptr qpow;
    acb_t s1, s2, s3, t1, t2;

    if (N < 2)
    {
        acb_set_ui(theta2, 2 * (N > 0));
        acb_set_ui(theta3, N > 0);
        acb_set(theta4, theta3);
        return;
    }

    if (N < 25)
    {
        acb_t q1, q2, q4, q8, q16;

        acb_init(q1);
        acb_init(q2);
        acb_init(q4);
        acb_init(q8);
        acb_init(q16);

        acb_set_round(q1, q, prec);

        if (N > 2) acb_mul(q2, q1, q1, prec);
        if (N > 4) acb_mul(q4, q2, q2, prec);
        if (N > 9) acb_mul(q8, q4, q4, prec);
        if (N > 16) acb_mul(q16, q8, q8, prec);

        /* theta2 = 2 + 2q^2 + 2q^4 [2q^2 + 2q^8 + 2q^16] */
        if (N > 6)
        {
            if (N > 12)
            {
                acb_add(theta2, q2, q8, prec);
                if (N > 20)
                    acb_add(theta2, theta2, q16, prec);
                acb_mul(theta2, theta2, q4, prec);
            }
            else
            {
                acb_mul(theta2, q2, q4, prec);
            }
            acb_add(theta2, theta2, q2, prec);
            acb_add_ui(theta2, theta2, 1, prec);
        }
        else if (N > 2)
            acb_add_ui(theta2, q2, 1, prec);
        else
            acb_one(theta2);

        acb_mul_2exp_si(theta2, theta2, 1);

        /* theta3 = [1 + 2q^4 + 2q^16] + [2q + 2q^9] */
        /* theta4 = [1 + 2q^4 + 2q^16] - [2q + 2q^9] */
        if (N > 4)
        {
            if (N > 16)
                acb_add(q4, q4, q16, prec);
            acb_mul_2exp_si(q4, q4, 1);
            acb_add_ui(q4, q4, 1, prec);

            if (N > 9)
                acb_addmul(q1, q1, q8, prec);
            acb_mul_2exp_si(q1, q1, 1);

            acb_add(theta3, q4, q1, prec);
            acb_sub(theta4, q4, q1, prec);
        }
        else
        {
            acb_mul_2exp_si(q1, q1, 1);
            acb_add_ui(theta3, q1, 1, prec);
            acb_sub_ui(theta4, q1, 1, prec);
            acb_neg(theta4, theta4);
        }

        acb_clear(q1);
        acb_clear(q2);
        acb_clear(q4);
        acb_clear(q8);
        acb_clear(q16);

        return;
    }

    mag_init(qmag);
    acb_init(s1);
    acb_init(s2);
    acb_init(s3);
    acb_init(t1);
    acb_init(t2);

    tab = flint_calloc(N, sizeof(slong));
    qpow = _acb_vec_init(N);

    for (k = 0; k*(k+1) < N; k++) tab[k*(k+1)] = -1;
    for (k = 0; 4*k*k < N; k++) tab[4*k*k] = -1;
    for (k = 0; 4*k*(k+1) + 1 < N; k++) tab[4*k*(k+1)] = -1;
    if (N > 0) tab[0] = 0;
    if (N > 1) tab[1] = 1;

    acb_modular_fill_addseq(tab, N);

    acb_get_mag(qmag, q);
    log2q_approx = mag_get_log2_d_approx(qmag);

    for (k = 0; k < N; 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, t1, t2, qpow + tab[k], qpow + k - tab[k], term_prec, prec);
        }
    }

    for (k = 0; k*(k+1) < N; k++) acb_add(s1, s1, qpow + k*(k+1), prec);
    for (k = 1; 4*k*k < N; k++) acb_add(s2, s2, qpow + 4*k*k, prec);
    for (k = 0; 4*k*(k+1) + 1 < N; k++) acb_add(s3, s3, qpow + 4*k*(k+1), prec);

    /*
    theta2 = 2 + 2q^2 + 2q^6 + 2q^12 + 2q^20 + 2q^30 + ...
    theta3 = 1 + 2 (q^4 + q^16 + ...) + 2q (1 + q^8 + q^24 + ...)
    theta4 = 1 + 2 (q^4 + q^16 + ...) - 2q (1 + q^8 + q^24 + ...)
    */
    acb_mul(s3, s3, q, prec);
    acb_mul_2exp_si(s3, s3, 1);
    acb_mul_2exp_si(s2, s2, 1);
    acb_add(theta3, s2, s3, prec);
    acb_sub(theta4, s2, s3, prec);
    acb_add_ui(theta3, theta3, 1, prec);
    acb_add_ui(theta4, theta4, 1, prec);
    acb_mul_2exp_si(theta2, s1, 1);
 
    _acb_vec_clear(qpow, N);
    flint_free(tab);

    acb_clear(s1);
    acb_clear(s2);
    acb_clear(s3);
    acb_clear(t1);
    acb_clear(t2);
    mag_clear(qmag);
}
Exemplo n.º 8
0
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);
}
Exemplo n.º 9
0
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);
}
Exemplo n.º 10
0
void
acb_hypgeom_2f1_continuation(acb_t res, acb_t res1,
    const acb_t a, const acb_t b, const acb_t c, const acb_t y,
    const acb_t z, const acb_t f0, const acb_t f1, long prec)
{
    mag_t A, nu, N, w, err, err1, R, T, goal;
    acb_t x;
    long j, k;

    mag_init(A);
    mag_init(nu);
    mag_init(N);
    mag_init(err);
    mag_init(err1);
    mag_init(w);
    mag_init(R);
    mag_init(T);
    mag_init(goal);
    acb_init(x);

    bound(A, nu, N, a, b, c, y, f0, f1);

    acb_sub(x, z, y, prec);

    /* |T(k)| <= A * binomial(N+k, k) * nu^k * |x|^k */
    acb_get_mag(w, x);
    mag_mul(w, w, nu); /* w = nu |x| */
    mag_mul_2exp_si(goal, A, -prec-2);

    /* bound for T(0) */
    mag_set(T, A);
    mag_inf(R);

    for (k = 1; k < 100 * prec; k++)
    {
        /* T(k) = T(k) * R(k), R(k) = (N+k)/k * w = (1 + N/k) w */
        mag_div_ui(R, N, k);
        mag_add_ui(R, R, 1);
        mag_mul(R, R, w);

        /* T(k) */
        mag_mul(T, T, R);

        if (mag_cmp(T, goal) <= 0 && mag_cmp_2exp_si(R, 0) < 0)
            break;
    }

    /* T(k) [1 + R + R^2 + R^3 + ...] */
    mag_geom_series(err, R, 0);
    mag_mul(err, T, err);

    /* Now compute T, R for the derivative */
    /* Coefficients are A * (k+1) * binomial(N+k+1, k+1) */
    mag_add_ui(T, N, 1);
    mag_mul(T, T, A);
    mag_inf(R);

    for (j = 1; j <= k; j++)
    {
        mag_add_ui(R, N, k + 1);
        mag_div_ui(R, R, k);
        mag_mul(R, R, w);
        mag_mul(T, T, R);
    }

    mag_geom_series(err1, R, 0);
    mag_mul(err1, T, err1);

    if (mag_is_inf(err))
    {
        acb_indeterminate(res);
        acb_indeterminate(res1);
    }
    else
    {
        evaluate_sum(res, res1, a, b, c, y, x, f0, f1, k, prec);

        acb_add_error_mag(res, err);
        acb_add_error_mag(res1, err1);
    }

    mag_clear(A);
    mag_clear(nu);
    mag_clear(N);
    mag_clear(err);
    mag_clear(err1);
    mag_clear(w);
    mag_clear(R);
    mag_clear(T);
    mag_clear(goal);
    acb_clear(x);
}
Exemplo n.º 11
0
/* computes the factors that are independent of n (all are upper bounds) */
void
acb_hypgeom_u_asymp_bound_factors(int * R, mag_t alpha,
    mag_t nu, mag_t sigma, mag_t rho, mag_t zinv,
    const acb_t a, const acb_t b, const acb_t z)
{
    mag_t r, u, zre, zim, zlo, sigma_prime;
    acb_t t;

    mag_init(r);
    mag_init(u);
    mag_init(zre);
    mag_init(zim);
    mag_init(zlo);
    mag_init(sigma_prime);
    acb_init(t);

    /* lower bounds for |re(z)|, |im(z)|, |z| */
    arb_get_mag_lower(zre, acb_realref(z));
    arb_get_mag_lower(zim, acb_imagref(z));
    acb_get_mag_lower(zlo, z); /* todo: hypot */

    /* upper bound for 1/|z| */
    mag_one(u);
    mag_div(zinv, u, zlo);

    /* upper bound for r = |b - 2a| */
    acb_mul_2exp_si(t, a, 1);
    acb_sub(t, b, t, MAG_BITS);
    acb_get_mag(r, t);

    /* determine region */
    *R = 0;

    if (mag_cmp(zlo, r) >= 0)
    {
        int znonneg = arb_is_nonnegative(acb_realref(z));

        if (znonneg && mag_cmp(zre, r) >= 0)
        {
            *R = 1;
        }
        else if (mag_cmp(zim, r) >= 0 || znonneg)
        {
            *R = 2;
        }
        else
        {
            mag_mul_2exp_si(u, r, 1);
            if (mag_cmp(zlo, u) >= 0)
                *R = 3;
        }
    }

    if (R == 0)
    {
        mag_inf(alpha);
        mag_inf(nu);
        mag_inf(sigma);
        mag_inf(rho);
    }
    else
    {
        /* sigma = |(b-2a)/z| */
        mag_mul(sigma, r, zinv);

        /* nu = (1/2 + 1/2 sqrt(1-4 sigma^2))^(-1/2) <= 1 + 2 sigma^2 */
        if (mag_cmp_2exp_si(sigma, -1) <= 0)
        {
            mag_mul(nu, sigma, sigma);
            mag_mul_2exp_si(nu, nu, 1);
            mag_one(u);
            mag_add(nu, nu, u);
        }
        else
        {
            mag_inf(nu);
        }

        /* modified sigma for alpha, beta, rho when in R3 */
        if (*R == 3)
            mag_mul(sigma_prime, sigma, nu);
        else
            mag_set(sigma_prime, sigma);

        /* alpha = 1/(1-sigma') */
        mag_one(alpha);
        mag_sub_lower(alpha, alpha, sigma_prime);
        mag_one(u);
        mag_div(alpha, u, alpha);

        /* rho = |2a^2-2ab+b|/2 + sigma'*(1+sigma'/4)/(1-sigma')^2 */
        mag_mul_2exp_si(rho, sigma_prime, -2);
        mag_one(u);
        mag_add(rho, rho, u);
        mag_mul(rho, rho, sigma_prime);
        mag_mul(rho, rho, alpha);
        mag_mul(rho, rho, alpha);
        acb_sub(t, a, b, MAG_BITS);
        acb_mul(t, t, a, MAG_BITS);
        acb_mul_2exp_si(t, t, 1);
        acb_add(t, t, b, MAG_BITS);
        acb_get_mag(u, t);
        mag_mul_2exp_si(u, u, -1);
        mag_add(rho, rho, u);
    }

    mag_clear(r);
    mag_clear(u);
    mag_clear(zre);
    mag_clear(zim);
    mag_clear(zlo);
    mag_clear(sigma_prime);
    acb_clear(t);
}
Exemplo n.º 12
0
int main()
{
    long iter;
    flint_rand_t state;

    printf("root_bound_fujiwara....");
    fflush(stdout);

    flint_randinit(state);

    for (iter = 0; iter < 10000; iter++)
    {
        acb_poly_t a;
        acb_ptr roots;
        acb_t t;
        mag_t mag1, mag2;
        long i, deg, prec;

        prec = 10 + n_randint(state, 400);
        deg = n_randint(state, 10);

        acb_init(t);
        acb_poly_init(a);
        mag_init(mag1);
        mag_init(mag2);
        roots = _acb_vec_init(deg);

        for (i = 0; i < deg; i++)
            acb_randtest(roots + i, state, prec, 1 + n_randint(state, 20));

        acb_poly_product_roots(a, roots, deg, prec);
        acb_randtest(t, state, prec, 1 + n_randint(state, 20));
        _acb_vec_scalar_mul(a->coeffs, a->coeffs, a->length, t, prec);

        acb_poly_root_bound_fujiwara(mag1, a);

        for (i = 0; i < deg; i++)
        {
            acb_get_mag(mag2, roots + i);

            /* acb_get_mag gives an upper bound which due to rounding
               could be larger than mag1, so we pick a slightly
               smaller number */
            mag_mul_ui(mag2, mag2, 10000);
            mag_div_ui(mag2, mag2, 10001);

            if (mag_cmp(mag2, mag1) > 0)
            {
                printf("FAIL\n");
                printf("a = "); acb_poly_printd(a, 15); printf("\n\n");
                printf("root = "); acb_printd(roots + i, 15); printf("\n\n");
                printf("mag1 = "); mag_printd(mag1, 10); printf("\n\n");
                printf("mag2 = "); mag_printd(mag2, 10); printf("\n\n");
                abort();
            }
        }

        _acb_vec_clear(roots, deg);
        acb_clear(t);
        acb_poly_clear(a);
        mag_clear(mag1);
        mag_clear(mag2);
    }

    flint_randclear(state);
    flint_cleanup();
    printf("PASS\n");
    return EXIT_SUCCESS;
}
Exemplo n.º 13
0
void
_acb_lambertw(acb_t res, const acb_t z, const acb_t ez1, const fmpz_t k, int flags, slong prec)
{
    slong goal, ebits, ebits2, ls, lt;
    const fmpz * expo;

    /* Estimated accuracy goal. */
    /* todo: account for exponent bits and bits in k. */
    goal = acb_rel_accuracy_bits(z);
    goal = FLINT_MAX(goal, 10);
    goal = FLINT_MIN(goal, prec);

    /* Handle tiny z directly. For k >= 2, |c_k| <= 4^k / 16. */
    if (fmpz_is_zero(k)
        && arf_cmpabs_2exp_si(arb_midref(acb_realref(z)), -goal / 2) < 0
        && arf_cmpabs_2exp_si(arb_midref(acb_imagref(z)), -goal / 2) < 0)
    {
        mag_t err;
        mag_init(err);
        acb_get_mag(err, z);
        mag_mul_2exp_si(err, err, 2);
        acb_set(res, z);
        acb_submul(res, res, res, prec);
        mag_geom_series(err, err, 3);
        mag_mul_2exp_si(err, err, -4);
        acb_add_error_mag(res, err);
        mag_clear(err);
        return;
    }

    if (arf_cmpabs(arb_midref(acb_realref(z)), arb_midref(acb_imagref(z))) >= 0)
        expo = ARF_EXPREF(arb_midref(acb_realref(z)));
    else
        expo = ARF_EXPREF(arb_midref(acb_imagref(z)));

    ebits = fmpz_bits(expo);

    /* ebits ~= log2(|log(z) + 2 pi i k|) */
    /* ebits2 ~= log2(log(log(z))) */
    ebits = FLINT_MAX(ebits, fmpz_bits(k));
    ebits = FLINT_MAX(ebits, 1) - 1;
    ebits2 = FLINT_BIT_COUNT(ebits);
    ebits2 = FLINT_MAX(ebits2, 1) - 1;

    /* We gain accuracy from the exponent when W ~ log - log log */
    if (fmpz_sgn(expo) > 0 || (fmpz_sgn(expo) < 0 && !fmpz_is_zero(k)))
    {
        goal += ebits - ebits2;
        goal = FLINT_MAX(goal, 10);
        goal = FLINT_MIN(goal, prec);

        /* The asymptotic series with truncation L, M gives us about 
           t - max(2+lt+L*(2+ls), M*(2+lt)) bits of accuracy where
           ls = -ebits, lt = ebits2 - ebits. */
        ls = 2 - ebits;
        lt = 2 + ebits2 - ebits;

        if (ebits - FLINT_MAX(lt + 1*ls, 1*lt) > goal)
        {
            acb_lambertw_asymp(res, z, k, 1, 1, goal);
            acb_set_round(res, res, prec);
            return;
        }
        else if (ebits - FLINT_MAX(lt + 3*ls, 5*lt) > goal)
        {
            acb_lambertw_asymp(res, z, k, 3, 5, goal);
            acb_set_round(res, res, prec);
            return;
        }
    }

    /* Extremely close to the branch point at -1/e, use the series expansion directly. */
    if (acb_lambertw_try_near_branch_point(res, z, ez1, k, flags, goal))
    {
        acb_set_round(res, res, prec);
        return;
    }

    /* compute union of both sides */
    if (acb_lambertw_branch_crossing(z, ez1, k))
    {
        acb_t za, zb, eza1, ezb1;
        fmpz_t kk;

        acb_init(za);
        acb_init(zb);
        acb_init(eza1);
        acb_init(ezb1);
        fmpz_init(kk);

        fmpz_neg(kk, k);

        acb_set(za, z);
        acb_conj(zb, z);
        arb_nonnegative_part(acb_imagref(za), acb_imagref(za));
        arb_nonnegative_part(acb_imagref(zb), acb_imagref(zb));

        acb_set(eza1, ez1);
        acb_conj(ezb1, ez1);
        arb_nonnegative_part(acb_imagref(eza1), acb_imagref(eza1));
        arb_nonnegative_part(acb_imagref(ezb1), acb_imagref(ezb1));

        /* Check series expansion again, because now there is no crossing. */
        if (!acb_lambertw_try_near_branch_point(res, za, eza1, k, flags, goal))
            acb_lambertw_cleared_cut_fix_small(za, za, eza1, k, flags, goal);

        if (!acb_lambertw_try_near_branch_point(res, zb, ezb1, kk, flags, goal))
            acb_lambertw_cleared_cut_fix_small(zb, zb, ezb1, kk, flags, goal);

        acb_conj(zb, zb);
        acb_union(res, za, zb, prec);

        acb_clear(za);
        acb_clear(zb);
        acb_clear(eza1);
        acb_clear(ezb1);
        fmpz_clear(kk);
    }
    else
    {
        acb_lambertw_cleared_cut_fix_small(res, z, ez1, k, flags, goal);
        acb_set_round(res, res, prec);
    }
}
Exemplo n.º 14
0
/* note: z should be exact here */
void acb_lambertw_main(acb_t res, const acb_t z,
                const acb_t ez1, const fmpz_t k, int flags, slong prec)
{
    acb_t w, t, oldw, ew;
    mag_t err;
    slong i, wp, accuracy, ebits, kbits, mbits, wp_initial, extraprec;
    int have_ew;

    acb_init(t);
    acb_init(w);
    acb_init(oldw);
    acb_init(ew);
    mag_init(err);

    /* We need higher precision for large k, large exponents, or very close
       to the branch point at -1/e. todo: we should be recomputing
       ez1 to higher precision when close... */
    acb_get_mag(err, z);
    if (fmpz_is_zero(k) && mag_cmp_2exp_si(err, 0) < 0)
        ebits = 0;
    else
        ebits = fmpz_bits(MAG_EXPREF(err));

    if (fmpz_is_zero(k) || (fmpz_is_one(k) && arb_is_negative(acb_imagref(z)))
                        || (fmpz_equal_si(k, -1) && arb_is_nonnegative(acb_imagref(z))))
    {
        acb_get_mag(err, ez1);
        mbits = -MAG_EXP(err);
        mbits = FLINT_MAX(mbits, 0);
        mbits = FLINT_MIN(mbits, prec);
    }
    else
    {
        mbits = 0;
    }

    kbits = fmpz_bits(k);

    extraprec = FLINT_MAX(ebits, kbits);
    extraprec = FLINT_MAX(extraprec, mbits);

    wp = wp_initial = 40 + extraprec;

    accuracy = acb_lambertw_initial(w, z, ez1, k, wp_initial);
    mag_zero(arb_radref(acb_realref(w)));
    mag_zero(arb_radref(acb_imagref(w)));

    /* We should be able to compute e^w for the final certification
       during the Halley iteration. */
    have_ew = 0;

    for (i = 0; i < 5 + FLINT_BIT_COUNT(prec + extraprec); i++)
    {
        /* todo: should we restart? */
        if (!acb_is_finite(w))
            break;

        wp = FLINT_MIN(3 * accuracy, 1.1 * prec + 10);
        wp = FLINT_MAX(wp, 40);
        wp += extraprec;

        acb_set(oldw, w);
        acb_lambertw_halley_step(t, ew, z, w, wp);

        /* estimate the error (conservatively) */
        acb_sub(w, w, t, wp);
        acb_get_mag(err, w);
        acb_set(w, t);
        acb_add_error_mag(t, err);
        accuracy = acb_rel_accuracy_bits(t);

        if (accuracy > 2 * extraprec)
            accuracy *= 2.9;  /* less conservatively */

        accuracy = FLINT_MIN(accuracy, wp);
        accuracy = FLINT_MAX(accuracy, 0);

        if (accuracy > prec + extraprec)
        {
            /* e^w = e^oldw * e^(w-oldw) */
            acb_sub(t, w, oldw, wp);
            acb_exp(t, t, wp);
            acb_mul(ew, ew, t, wp);
            have_ew = 1;
            break;
        }

        mag_zero(arb_radref(acb_realref(w)));
        mag_zero(arb_radref(acb_imagref(w)));
    }

    wp = FLINT_MIN(3 * accuracy, 1.1 * prec + 10);
    wp = FLINT_MAX(wp, 40);
    wp += extraprec;

    if (acb_lambertw_check_branch(w, k, wp))
    {
        acb_t u, r, eu1;
        mag_t err, rad;

        acb_init(u);
        acb_init(r);
        acb_init(eu1);

        mag_init(err);
        mag_init(rad);

        if (have_ew)
            acb_set(t, ew);
        else
            acb_exp(t, w, wp);
        /* t = w e^w */
        acb_mul(t, t, w, wp);

        acb_sub(r, t, z, wp);

        /* Bound W' on the straight line path between t and z */
        acb_union(u, t, z, wp);

        arb_const_e(acb_realref(eu1), wp);
        arb_zero(acb_imagref(eu1));
        acb_mul(eu1, eu1, u, wp);
        acb_add_ui(eu1, eu1, 1, wp);

        if (acb_lambertw_branch_crossing(u, eu1, k))
        {
            mag_inf(err);
        }
        else
        {
            acb_lambertw_bound_deriv(err, u, eu1, k);
            acb_get_mag(rad, r);
            mag_mul(err, err, rad);
        }

        acb_add_error_mag(w, err);

        acb_set(res, w);

        acb_clear(u);
        acb_clear(r);
        acb_clear(eu1);
        mag_clear(err);
        mag_clear(rad);
    }
    else
    {
        acb_indeterminate(res);
    }

    acb_clear(t);
    acb_clear(w);
    acb_clear(oldw);
    acb_clear(ew);
    mag_clear(err);
}
Exemplo n.º 15
0
static void
acb_log_sin_pi_half(acb_t res, const acb_t z, slong prec, int upper)
{
    acb_t t, u, zmid;
    arf_t n;
    arb_t pi;

    acb_init(t);
    acb_init(u);
    acb_init(zmid);
    arf_init(n);
    arb_init(pi);

    arf_set(arb_midref(acb_realref(zmid)), arb_midref(acb_realref(z)));
    arf_set(arb_midref(acb_imagref(zmid)), arb_midref(acb_imagref(z)));

    arf_floor(n, arb_midref(acb_realref(zmid)));
    arb_sub_arf(acb_realref(zmid), acb_realref(zmid), n, prec);

    arb_const_pi(pi, prec);

    if (arf_cmpabs_2exp_si(arb_midref(acb_imagref(zmid)), 2) < 1)
    {
        acb_sin_pi(t, zmid, prec);
        acb_log(t, t, prec);
    }
    else  /* i*pi*(z-0.5) + log((1-exp(-2i*pi*z))/2) */
    {
        acb_mul_2exp_si(t, zmid, 1);
        acb_neg(t, t);

        if (upper)
            acb_conj(t, t);

        acb_exp_pi_i(t, t, prec);
        acb_sub_ui(t, t, 1, prec);
        acb_neg(t, t);

        acb_mul_2exp_si(t, t, -1);

        acb_log(t, t, prec);
        acb_one(u);
        acb_mul_2exp_si(u, u, -1);
        acb_sub(u, zmid, u, prec);
        if (upper)
            acb_conj(u, u);
        acb_mul_onei(u, u);
        acb_addmul_arb(t, u, pi, prec);
        if (upper)
            acb_conj(t, t);
    }

    if (upper)
        arb_submul_arf(acb_imagref(t), pi, n, prec);
    else
        arb_addmul_arf(acb_imagref(t), pi, n, prec);

    /* propagated error bound from the derivative pi cot(pi z) */
    if (!acb_is_exact(z))
    {
        mag_t zm, um;

        mag_init(zm);
        mag_init(um);

        acb_cot_pi(u, z, prec);
        acb_mul_arb(u, u, pi, prec);

        mag_hypot(zm, arb_radref(acb_realref(z)), arb_radref(acb_imagref(z)));
        acb_get_mag(um, u);
        mag_mul(um, um, zm);

        acb_add_error_mag(t, um);

        mag_clear(zm);
        mag_clear(um);
    }

    acb_set(res, t);

    acb_clear(t);
    acb_clear(u);
    acb_clear(zmid);
    arf_clear(n);
    arb_clear(pi);
}
Exemplo n.º 16
0
/* error propagation based on derivatives */
void
acb_hypgeom_airy_direct_prop(acb_t ai, acb_t aip, acb_t bi, acb_t bip,
    const acb_t z, slong n, slong prec)
{
    mag_t aib, aipb, bib, bipb, zb, rad;
    acb_t zz;
    int real;

    mag_init(aib);
    mag_init(aipb);
    mag_init(bib);
    mag_init(bipb);
    mag_init(zb);
    mag_init(rad);
    acb_init(zz);

    real = acb_is_real(z);
    arf_set(arb_midref(acb_realref(zz)), arb_midref(acb_realref(z))); 
    arf_set(arb_midref(acb_imagref(zz)), arb_midref(acb_imagref(z))); 
    mag_hypot(rad, arb_radref(acb_realref(z)), arb_radref(acb_imagref(z)));
    acb_get_mag(zb, z);

    acb_hypgeom_airy_bound(aib, aipb, bib, bipb, z);
    acb_hypgeom_airy_direct(ai, aip, bi, bip, zz, n, prec);

    if (ai != NULL)
    {
        mag_mul(aipb, aipb, rad);
        if (real)
            arb_add_error_mag(acb_realref(ai), aipb);
        else
            acb_add_error_mag(ai, aipb);
    }

    if (aip != NULL)
    {
        mag_mul(aib, aib, rad);
        mag_mul(aib, aib, zb);  /* |Ai''(z)| = |z Ai(z)| */
        if (real)
            arb_add_error_mag(acb_realref(aip), aib);
        else
            acb_add_error_mag(aip, aib);
    }

    if (bi != NULL)
    {
        mag_mul(bipb, bipb, rad);
        if (real)
            arb_add_error_mag(acb_realref(bi), bipb);
        else
            acb_add_error_mag(bi, bipb);
    }

    if (bip != NULL)
    {
        mag_mul(bib, bib, rad);
        mag_mul(bib, bib, zb);  /* |Bi''(z)| = |z Bi(z)| */
        if (real)
            arb_add_error_mag(acb_realref(bip), bib);
        else
            acb_add_error_mag(bip, bib);
    }

    mag_clear(aib);
    mag_clear(aipb);
    mag_clear(bib);
    mag_clear(bipb);
    mag_clear(zb);
    mag_clear(rad);
    acb_clear(zz);
}
Exemplo n.º 17
0
/* todo: use log(1-z) when this is better? would also need to
   adjust strategy in the main function */
void
acb_hypgeom_dilog_bernoulli(acb_t res, const acb_t z, slong prec)
{
    acb_t s, w, w2;
    slong n, k;
    fmpz_t c, d;
    mag_t m, err;
    double lm;
    int real;

    acb_init(s);
    acb_init(w);
    acb_init(w2);
    fmpz_init(c);
    fmpz_init(d);
    mag_init(m);
    mag_init(err);

    real = 0;
    if (acb_is_real(z))
    {
        arb_sub_ui(acb_realref(w), acb_realref(z), 1, 30);
        real = arb_is_nonpositive(acb_realref(w));
    }

    acb_log(w, z, prec);
    acb_get_mag(m, w);

    /* for k >= 4, the terms are bounded by  (|w| / (2 pi))^k */
    mag_set_ui_2exp_si(err, 2670177, -24);  /* upper bound for 1/(2pi) */
    mag_mul(err, err, m);
    lm = mag_get_d_log2_approx(err);

    if (lm < -0.25)
    {
        n = prec / (-lm) + 1;
        n = FLINT_MAX(n, 4);
        mag_geom_series(err, err, n);

        BERNOULLI_ENSURE_CACHED(n)

        acb_mul(w2, w, w, prec);

        for (k = n - (n % 2 == 0); k >= 3; k -= 2)
        {
            fmpz_mul_ui(c, fmpq_denref(bernoulli_cache + k - 1), k - 1);
            fmpz_mul_ui(d, c, (k + 1) * (k + 2));
            acb_mul(s, s, w2, prec);
            acb_mul_fmpz(s, s, c, prec);
            fmpz_mul_ui(c, fmpq_numref(bernoulli_cache + k - 1), (k + 1) * (k + 2));
            acb_sub_fmpz(s, s, c, prec);
            acb_div_fmpz(s, s, d, prec);
        }

        acb_mul(s, s, w, prec);
        acb_mul_2exp_si(s, s, 1);
        acb_sub_ui(s, s, 3, prec);
        acb_mul(s, s, w2, prec);
        acb_mul_2exp_si(s, s, -1);
        acb_const_pi(w2, prec);
        acb_addmul(s, w2, w2, prec);
        acb_div_ui(s, s, 6, prec);

        acb_neg(w2, w);
        acb_log(w2, w2, prec);
        acb_submul(s, w2, w, prec);
        acb_add(res, s, w, prec);

        acb_add_error_mag(res, err);
        if (real)
            arb_zero(acb_imagref(res));
    }
    else
    {
        acb_indeterminate(res);
    }

    acb_clear(s);
    acb_clear(w);
    acb_clear(w2);
    fmpz_clear(c);
    fmpz_clear(d);
    mag_clear(m);
    mag_clear(err);
}
Exemplo n.º 18
0
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);
}
Exemplo n.º 19
0
int main()
{
    slong iter;
    flint_rand_t state;

    flint_printf("2f1_continuation....");
    fflush(stdout);

    flint_randinit(state);

    for (iter = 0; iter < 1000 * arb_test_multiplier(); iter++)
    {
        acb_t a, b, c, z1, z2, f1, f2, g1, g2, h1, h2, aa, bb, cc;
        mag_t d0, d1, dt;

        slong prec;
        int regularized, ebits;

        acb_init(a); acb_init(b); acb_init(c);
        acb_init(aa); acb_init(bb); acb_init(cc);
        acb_init(z1); acb_init(z2);
        acb_init(f1); acb_init(f2);
        acb_init(g1); acb_init(g2);
        acb_init(h1); acb_init(h2);
        mag_init(d0); mag_init(d1); mag_init(dt);

        prec = 2 + n_randint(state, 300);
        ebits = 10;
        regularized = n_randint(state, 2);

        acb_randtest_param(a, state, 1 + n_randint(state, 400), 1 + n_randint(state, ebits / 2));
        acb_randtest_param(b, state, 1 + n_randint(state, 400), 1 + n_randint(state, ebits / 2));
        acb_randtest_param(c, state, 1 + n_randint(state, 400), 1 + n_randint(state, ebits / 2));
        acb_randtest(h1, state, 1 + n_randint(state, 400), 1 + n_randint(state, ebits));
        acb_randtest(h2, state, 1 + n_randint(state, 400), 1 + n_randint(state, ebits));

        do {
            int left, upper, lower;

            acb_randtest_param(z1, state, 1 + n_randint(state, 400), 1 + n_randint(state, ebits));
            acb_randtest_param(z2, state, 1 + n_randint(state, 400), 1 + n_randint(state, ebits));

            /* we test both convergent and non-convergent cases, but
               try to be more efficient by generating more convergent cases */
            if (n_randint(state, 2))
            {
                acb_sub_ui(aa, z1, 1, prec);
                acb_get_mag(d0, z1);
                acb_get_mag(d1, aa);
                acb_get_mag(dt, z2);

                if (mag_cmp(dt, d0) >= 0 || mag_cmp(dt, d1) >= 0)
                    continue;
            }

            acb_add(z2, z1, z2, prec);

            /* for the test, don't cross the branch cut */
            acb_sub_ui(aa, z1, 1, prec);
            acb_sub_ui(bb, z2, 1, prec);

            left = arb_is_negative(acb_realref(aa)) && arb_is_negative(acb_realref(bb));
            upper = arb_is_positive(acb_imagref(aa)) && arb_is_positive(acb_imagref(bb));
            lower = arb_is_nonpositive(acb_imagref(aa)) && arb_is_nonpositive(acb_imagref(bb));

            if (left || upper || lower)
                break;
        } while (1);

        acb_add_ui(aa, a, 1, prec);
        acb_add_ui(bb, b, 1, prec);
        acb_add_ui(cc, c, 1, prec);

        acb_hypgeom_2f1(f1, a, b, c, z1, regularized, prec);
        acb_hypgeom_2f1(f2, aa, bb, cc, z1, regularized, prec);
        acb_mul(f2, f2, a, prec);
        acb_mul(f2, f2, b, prec);
        if (!regularized)
            acb_div(f2, f2, c, prec);

        acb_hypgeom_2f1_continuation(h1, h2, a, b, c, z1, z2, f1, f2, prec);

        if (acb_is_finite(h1) || acb_is_finite(h2))
        {
            acb_hypgeom_2f1(g1, a, b, c, z2, regularized, prec);
            acb_hypgeom_2f1(g2, aa, bb, cc, z2, regularized, prec);
            acb_mul(g2, g2, a, prec);
            acb_mul(g2, g2, b, prec);
            if (!regularized)
                acb_div(g2, g2, c, prec);

            if (!acb_overlaps(g1, h1) || !acb_overlaps(g2, h2))
            {
                flint_printf("FAIL: consistency\n\n");
                flint_printf("regularized = %d, prec = %wd\n\n", regularized, prec);
                flint_printf("a = "); acb_printd(a, 30); flint_printf("\n\n");
                flint_printf("b = "); acb_printd(b, 30); flint_printf("\n\n");
                flint_printf("c = "); acb_printd(c, 30); flint_printf("\n\n");
                flint_printf("z1 = "); acb_printd(z1, 30); flint_printf("\n\n");
                flint_printf("z2 = "); acb_printd(z2, 30); flint_printf("\n\n");
                flint_printf("F(a,b,c,z1) and F'(a,b,c,z1):\n");
                flint_printf("f1 = "); acb_printd(f1, 30); flint_printf("\n\n");
                flint_printf("f2 = "); acb_printd(f2, 30); flint_printf("\n\n");
                flint_printf("F(a,b,c,z2) and F'(a,b,c,z2):\n");
                flint_printf("g1 = "); acb_printd(g1, 30); flint_printf("\n\n");
                flint_printf("g2 = "); acb_printd(g2, 30); flint_printf("\n\n");
                flint_printf("Computed F and F':\n");
                flint_printf("h1 = "); acb_printd(h1, 30); flint_printf("\n\n");
                flint_printf("h2 = "); acb_printd(h2, 30); flint_printf("\n\n");
                flint_abort();
            }
        }

        acb_clear(a); acb_clear(b); acb_clear(c);
        acb_clear(aa); acb_clear(bb); acb_clear(cc);
        acb_clear(z1); acb_clear(z2);
        acb_clear(f1); acb_clear(f2);
        acb_clear(g1); acb_clear(g2);
        acb_clear(h1); acb_clear(h2);
        mag_clear(d0); mag_clear(d1); mag_clear(dt);
    }

    flint_randclear(state);
    flint_cleanup();
    flint_printf("PASS\n");
    return EXIT_SUCCESS;
}
void
acb_rising_ui_get_mag(mag_t bound, const acb_t s, ulong n)
{
    if (n == 0)
    {
        mag_one(bound);
        return;
    }

    if (n == 1)
    {
        acb_get_mag(bound, s);
        return;
    }

    if (!acb_is_finite(s))
    {
        mag_inf(bound);
        return;
    }

    if (arf_sgn(arb_midref(acb_realref(s))) >= 0)
    {
        acb_rising_get_mag2_right(bound, acb_realref(s), acb_imagref(s), n);
    }
    else
    {
        arb_t a;
        long k;
        mag_t bound2, t, u;

        arb_init(a);
        mag_init(bound2);
        mag_init(t);
        mag_init(u);

        arb_get_mag(u, acb_imagref(s));
        mag_mul(u, u, u);
        mag_one(bound);

        for (k = 0; k < n; k++)
        {
            arb_add_ui(a, acb_realref(s), k, MAG_BITS);

            if (arf_sgn(arb_midref(a)) >= 0)
            {
                acb_rising_get_mag2_right(bound2, a, acb_imagref(s), n - k);
                mag_mul(bound, bound, bound2);
                break;
            }
            else
            {
                arb_get_mag(t, a);
                mag_mul(t, t, t);
                mag_add(t, t, u);
                mag_mul(bound, bound, t);
            }
        }

        arb_clear(a);
        mag_clear(bound2);
        mag_clear(t);
        mag_clear(u);
    }

    mag_sqrt(bound, bound);
}