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;

    /* default algorithm to choose number of terms */
    if (n < 0)
    {
        n = acb_hypgeom_pfq_series_choose_n(a, p, b, q, z, len, prec);
    }

    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 (acb_poly_length(t) != 0)
    {
        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);

        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);
}
Exemple #2
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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);
}