mirror of
https://github.com/vale981/arb
synced 2025-03-06 01:41:39 -05:00
102 lines
2.5 KiB
C
102 lines
2.5 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) 2013 Fredrik Johansson
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******************************************************************************/
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#include "gamma.h"
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static void
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bsplit(fmprb_t y, const fmpz_t p, const fmpz_t q, ulong a, ulong b, long prec)
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{
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if (b - a <= 8)
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{
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fmpz_t t, u;
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ulong c;
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fmpz_init(t);
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fmpz_init(u);
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fmpz_mul_ui(t, q, a);
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fmpz_add(t, t, p);
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fmpz_set(u, t);
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for (c = a + 1; c < b; c++)
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{
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fmpz_add(u, u, q);
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fmpz_mul(t, t, u);
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}
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fmprb_set_round_fmpz(y, t, prec);
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fmpz_clear(t);
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fmpz_clear(u);
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}
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else
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{
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fmprb_t w;
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ulong m = a + (b - a) / 2;
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fmprb_init(w);
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bsplit(y, p, q, a, m, prec);
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bsplit(w, p, q, m, b, prec);
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fmprb_mul(y, y, w, prec);
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fmprb_clear(w);
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}
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}
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void
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gamma_rising_fmprb_fmpq_ui_bsplit(fmprb_t y, const fmpq_t x, ulong n, long prec)
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{
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if (n == 0)
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{
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fmprb_one(y);
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}
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else if (n == 1)
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{
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fmprb_set_fmpq(y, x, prec);
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}
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else
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{
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long wp;
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wp = FMPR_PREC_ADD(prec, FLINT_BIT_COUNT(n));
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bsplit(y, fmpq_numref(x), fmpq_denref(x), 0, n, wp);
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if (fmpz_is_one(fmpq_denref(x)))
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{
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fmprb_set_round(y, y, prec);
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}
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else
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{
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fmprb_t t;
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fmprb_init(t);
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fmprb_set_fmpz(t, fmpq_denref(x));
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fmprb_pow_ui(t, t, n, wp);
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fmprb_div(y, y, t, prec);
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fmprb_clear(t);
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}
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}
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}
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