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/*
Copyright (C) 2014 Fredrik Johansson
This file is part of FLINT.
FLINT 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 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "acb.h"
#include "acb_hypgeom.h"
void
acb_hypgeom_pfq_sum_forward(acb_t s, acb_t t,
acb_srcptr a, slong p, acb_srcptr b, slong q, const acb_t z, slong n, slong prec)
{
acb_t u, v;
slong k, i;
acb_init(u);
acb_init(v);
acb_zero(s);
acb_one(t);
for (k = 0; k < n && !acb_is_zero(t); k++)
{
acb_add(s, s, t, prec);
if (p > 0)
{
acb_add_ui(u, a, k, prec);
for (i = 1; i < p; i++)
{
acb_add_ui(v, a + i, k, prec);
acb_mul(u, u, v, prec);
}
acb_mul(t, t, u, prec);
}
if (q > 0)
{
acb_add_ui(u, b, k, prec);
for (i = 1; i < q; i++)
{
acb_add_ui(v, b + i, k, prec);
acb_mul(u, u, v, prec);
}
acb_div(t, t, u, prec);
}
acb_mul(t, t, z, prec);
}
acb_clear(u);
acb_clear(v);
}