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/*
Copyright (C) 2021 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 "arb_hypgeom/impl.h"
#include "acb.h"
#include "acb_hypgeom.h"
void
acb_hypgeom_rising_ui_forward(acb_t res, const acb_t x, ulong n, slong prec)
{
acb_t t;
ulong k;
slong wp;
if (n <= 1)
{
if (n == 0)
acb_one(res);
else
acb_set_round(res, x, prec);
return;
}
wp = prec + FLINT_BIT_COUNT(n);
acb_init(t);
acb_add_ui(t, x, 1, wp);
acb_mul(res, x, t, (n == 2) ? prec : wp);
for (k = 2; k < n; k++)
{
_arb_increment_fast(acb_realref(t), wp);
acb_mul(res, res, t, k == (n - 1) ? prec : wp);
}
acb_clear(t);
}