arb/arb_poly/evaluate_acb_horner.c
2015-11-05 17:59:29 +00:00

73 lines
2 KiB
C

/*=============================================================================
This file is part of ARB.
ARB is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
ARB is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with ARB; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2010 Sebastian Pancratz
Copyright (C) 2012 Fredrik Johansson
******************************************************************************/
#include "arb_poly.h"
void
_arb_poly_evaluate_acb_horner(acb_t y, arb_srcptr f, slong len,
const acb_t x, slong prec)
{
if (len == 0)
{
acb_zero(y);
}
else if (len == 1 || acb_is_zero(x))
{
acb_set_round_arb(y, f, prec);
}
else if (len == 2)
{
acb_mul_arb(y, x, f + 1, prec);
acb_add_arb(y, y, f + 0, prec);
}
else
{
slong i = len - 1;
acb_t t, u;
acb_init(t);
acb_init(u);
acb_set_arb(u, f + i);
for (i = len - 2; i >= 0; i--)
{
acb_mul(t, u, x, prec);
acb_add_arb(u, t, f + i, prec);
}
acb_swap(y, u);
acb_clear(t);
acb_clear(u);
}
}
void
arb_poly_evaluate_acb_horner(acb_t res, const arb_poly_t f, const acb_t a, slong prec)
{
_arb_poly_evaluate_acb_horner(res, f->coeffs, f->length, a, prec);
}