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https://github.com/vale981/arb
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51 lines
1.6 KiB
C
51 lines
1.6 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) 2016 Fredrik Johansson
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******************************************************************************/
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#include "acb_dirichlet.h"
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void
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acb_dirichlet_eta(acb_t res, const acb_t s, slong prec)
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{
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if (acb_is_one(s))
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{
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arb_const_log2(acb_realref(res), prec);
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arb_zero(acb_imagref(res));
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}
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else
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{
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acb_t t;
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acb_init(t);
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acb_one(t);
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acb_mul_2exp_si(t, t, -1);
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acb_pow(t, t, s, prec);
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acb_mul_2exp_si(t, t, 1);
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acb_sub_ui(t, t, 1, prec);
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acb_neg(t, t);
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acb_zeta(res, s, prec);
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acb_mul(res, res, t, prec);
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acb_clear(t);
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}
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}
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