mirror of
https://github.com/vale981/arb
synced 2025-03-06 01:41:39 -05:00
87 lines
2.4 KiB
C
87 lines
2.4 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) 2012 Fredrik Johansson
|
|
|
|
******************************************************************************/
|
|
|
|
#include "fmpcb.h"
|
|
|
|
static ulong choose_M(ulong N, long target)
|
|
{
|
|
return FLINT_MIN(N, target);
|
|
}
|
|
|
|
void
|
|
fmpcb_zeta_em_choose_param(fmpr_t bound, ulong * N, ulong * M, const fmpcb_t s, long target, long prec)
|
|
{
|
|
ulong A, B, C;
|
|
fmpr_t Abound, Bbound, Cbound, tol;
|
|
|
|
fmpr_init(Abound);
|
|
fmpr_init(Bbound);
|
|
fmpr_init(Cbound);
|
|
fmpr_init(tol);
|
|
|
|
fmpr_set_si_2exp_si(tol, 1, -target);
|
|
|
|
A = 1;
|
|
B = 2;
|
|
|
|
fmpcb_zeta_em_bound(Bbound, s, B, choose_M(B, target), prec);
|
|
|
|
if (fmpr_cmp(Bbound, tol) > 0)
|
|
{
|
|
while (fmpr_cmp(Bbound, tol) > 0)
|
|
{
|
|
fmpr_set(Abound, Bbound);
|
|
A *= 2;
|
|
B *= 2;
|
|
fmpcb_zeta_em_bound(Bbound, s, B, choose_M(B, target), prec);
|
|
}
|
|
|
|
/* bisect (-A, B] */
|
|
while (B > A + 4)
|
|
{
|
|
C = A + (B - A) / 2;
|
|
fmpcb_zeta_em_bound(Cbound, s, C, choose_M(C, target), prec);
|
|
if (fmpr_cmp(Cbound, tol) < 0)
|
|
{
|
|
B = C;
|
|
fmpr_set(Bbound, Cbound);
|
|
}
|
|
else
|
|
{
|
|
A = C;
|
|
fmpr_set(Abound, Cbound);
|
|
}
|
|
}
|
|
}
|
|
|
|
fmpr_set(bound, Bbound);
|
|
*N = B;
|
|
*M = choose_M(B, target);
|
|
|
|
fmpr_clear(Abound);
|
|
fmpr_clear(Bbound);
|
|
fmpr_clear(Cbound);
|
|
fmpr_clear(tol);
|
|
}
|