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https://github.com/vale981/arb
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74 lines
2.1 KiB
C
74 lines
2.1 KiB
C
/*=============================================================================
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This file is part of ARB.
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ARB is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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ARB is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with ARB; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2012 Fredrik Johansson
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******************************************************************************/
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#include <math.h>
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#include "arith.h"
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#include "fmprb.h"
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static void
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fmprb_zeta_ui_mpfr(fmprb_t x, ulong n, long prec)
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{
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mpfr_t t;
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mpfr_init2(t, prec);
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mpfr_zeta_ui(t, n, MPFR_RNDD);
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fmprb_zero(x);
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fmpr_set_mpfr(fmprb_midref(x), t);
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fmprb_add_error_2exp_si(x, mpfr_get_exp(t)-prec);
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mpfr_clear(t);
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}
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void
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fmprb_zeta_ui(fmprb_t x, ulong n, long prec)
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{
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/* asymptotic case */
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if (n == 0 || n > 0.7 * prec)
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{
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fmprb_zeta_ui_mpfr(x, n, prec);
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}
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else if (n == 3)
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{
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fmprb_const_zeta3_bsplit(x, prec);
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}
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/* small even n */
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else if ((n % 2 == 0) && (n < 40 + 0.11*prec))
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{
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fmprb_zeta_ui_bernoulli(x, n, prec);
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}
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/* small odd n, extremely high precision */
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else if (n < prec * 0.0006)
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{
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fmprb_zeta_ui_bsplit(x, n, prec);
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}
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/* large n */
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else if (prec > 20 && n > 0.4 * pow(prec, 0.8))
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{
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fmprb_zeta_ui_euler_product(x, n, prec);
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}
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/* fallback */
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else
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{
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fmprb_zeta_ui_mpfr(x, n, prec);
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}
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}
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