arb/gamma/taylor_bound_remainder.c

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/*=============================================================================
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) 2013 Fredrik Johansson
******************************************************************************/
#include "gamma.h"
void
gamma_taylor_bound_remainder(fmpr_t err, const fmpr_t z, long n)
{
fmpr_t t, u;
gamma_taylor_bound_extend_cache(n + 1);
fmpr_init(t);
fmpr_init(u);
/* denominator: 1 - r(n+1) * z, rounded down */
fmpr_mul(t, gamma_taylor_bound_ratio_cache + n + 1,
z, FMPRB_RAD_PREC, FMPR_RND_UP);
fmpr_one(u);
fmpr_sub(u, u, t, FMPRB_RAD_PREC, FMPR_RND_DOWN);
if (fmpr_sgn(u) <= 0)
{
fmpr_pos_inf(err);
}
else
{
fmpr_pow_sloppy_ui(t, z, n, FMPRB_RAD_PREC, FMPR_RND_UP);
fmpr_mul_2exp_si(t, t, gamma_taylor_bound_mag_cache[n + 1]);
fmpr_div(err, t, u, FMPRB_RAD_PREC, FMPR_RND_UP);
}
fmpr_clear(t);
fmpr_clear(u);
}