mirror of
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) 2012 Fredrik Johansson
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******************************************************************************/
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#include "fmprb.h"
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/* sets y = x / (2^n - 1) */
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/* XXX: for huge n, use better algorithm / fix overflow in the loop */
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void
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fmprb_div_2expm1_ui(fmprb_t y, const fmprb_t x, ulong n, long prec)
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{
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fmpz_t t;
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fmprb_t u;
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long i;
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fmpz_init(t);
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fmprb_init(u);
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for (i = prec; i >= 0; i -= n)
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fmpz_setbit(t, i);
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fmpr_set_fmpz(fmprb_midref(u), t);
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fmpr_one(fmprb_radref(u));
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fmprb_mul(y, x, u, prec);
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fmprb_mul_2exp_si(y, y, -prec-n);
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fmpz_clear(t);
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fmprb_clear(u);
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}
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