mirror of
https://github.com/vale981/arb
synced 2025-03-06 01:41:39 -05:00
89 lines
2.3 KiB
C
89 lines
2.3 KiB
C
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/*=============================================================================
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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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void
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gamma_fmpq_outward(fmprb_t y, const fmpq_t x, long prec)
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{
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fmpq_t a;
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fmpz_t n;
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fmpz p, q;
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long m;
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fmprb_t t, u;
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fmpq_init(a);
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fmpz_init(n);
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fmprb_init(t);
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fmprb_init(u);
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/* write x = a + n with 0 < a <= 1 */
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if (fmpz_is_one(fmpq_denref(x)))
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{
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fmpq_one(a);
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fmpz_sub_ui(n, fmpq_numref(x), 1);
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}
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else
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{
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fmpz_fdiv_qr(n, fmpq_numref(a), fmpq_numref(x), fmpq_denref(x));
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fmpz_set(fmpq_denref(a), fmpq_denref(x));
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}
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if (!fmpz_fits_si(n))
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{
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printf("gamma: too large fmpq to reduce to 0!\n");
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abort();
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}
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m = fmpz_get_si(n);
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/* evaluate gamma(a) */
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p = *fmpq_numref(a);
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q = *fmpq_denref(a);
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if (q == 1 || q == 2 || q == 3 || q == 4 || q == 6)
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gamma_small_frac(t, p, q, prec);
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else
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gamma_series_fmpq_hypgeom(t, a, 1, prec);
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/* argument reduction */
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if (m >= 0)
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{
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gamma_rising_fmprb_fmpq_ui_bsplit(u, a, m, prec);
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fmprb_mul(y, t, u, prec);
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}
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else
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{
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gamma_rising_fmprb_fmpq_ui_bsplit(u, x, -m, prec);
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fmprb_div(y, t, u, prec);
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}
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fmpq_clear(a);
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fmpz_clear(n);
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fmprb_clear(t);
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fmprb_clear(u);
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}
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