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/*
Copyright (C) 2016 Fredrik Johansson
This file is part of Arb.
Arb is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version. See <http://www.gnu.org/licenses/>.
*/
#include "acb_hypgeom.h"
void
acb_hypgeom_pfq_series_sum(acb_poly_t s, acb_poly_t t,
const acb_poly_struct * a, slong p,
const acb_poly_struct * b, slong q,
const acb_poly_t z, int regularized,
slong n, slong len, slong prec)
{
slong abits, zbits, i, j, cb;
if (n < 4)
{
acb_hypgeom_pfq_series_sum_forward(s, t, a, p, b, q, z,
regularized, n, len, prec);
return;
}
abits = 0;
zbits = 0;
for (i = 0; i < p; i++)
{
for (j = 0; j < FLINT_MIN(acb_poly_length(a + i), n); j++)
{
cb = acb_bits((a + i)->coeffs + j);
abits = FLINT_MAX(abits, cb);
}
}
for (i = 0; i < q; i++)
{
for (j = 0; j < FLINT_MIN(acb_poly_length(b + i), n); j++)
{
cb = acb_bits((b + i)->coeffs + j);
abits = FLINT_MAX(abits, cb);
}
}
for (j = 0; j < FLINT_MIN(acb_poly_length(z), n); j++)
{
cb = acb_bits(z->coeffs + j);
zbits = FLINT_MAX(zbits, cb);
}
/* Prefer RS with small coefficients in parameters, large coefficients
in z. TODO: tune for larger len? */
if (len <= 5 && prec > 900 && abits < prec * 0.1 && zbits > prec * 0.1)
{
acb_hypgeom_pfq_series_sum_rs(s, t, a, p, b, q, z,
regularized, n, len, prec);
return;
}
/* Prefer BS with small coefficients and high precision, or when
computing derivatives of high order. */
if ((abits < prec * 0.1 && zbits < prec * 0.1 && prec > 600) || len > 20)
{
acb_hypgeom_pfq_series_sum_bs(s, t, a, p, b, q, z,
regularized, n, len, prec);
return;
}
/* TODO: also use bs here when n is large enough, for better
numerical stability? */
acb_hypgeom_pfq_series_sum_forward(s, t, a, p, b, q, z,
regularized, n, len, prec);
}
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