69 lines
1.9 KiB
C
69 lines
1.9 KiB
C
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/*=============================================================================
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This file is part of FLINT.
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FLINT 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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FLINT 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 FLINT; 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) 2011 Fredrik Johansson
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******************************************************************************/
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#include <math.h>
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#include "arith.h"
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void arith_landau_function_vec(fmpz * res, slong len)
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{
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mp_limb_t p, pmax;
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mp_limb_t pk, pkhi;
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fmpz_t a;
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ulong k, n;
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if (len < 1)
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return;
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for (k = 0; k < len; k++)
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fmpz_one(res + k);
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pmax = 1.328 * sqrt(len*log(len) + 1);
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fmpz_init(a);
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for (p = UWORD(2); p <= pmax; p = n_nextprime(p, 0))
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{
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for (n = len - 1; n >= p; n--)
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{
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pk = p;
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pkhi = UWORD(0);
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for (k = 1; k <= len; k++)
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{
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if (pk > n || pkhi)
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break;
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fmpz_mul_ui(a, res + n - pk, pk);
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if (fmpz_cmp(res + n, a) < 0)
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fmpz_set(res + n, a);
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umul_ppmm(pkhi, pk, pk, p);
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}
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}
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}
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fmpz_clear(a);
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}
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