88 lines
2.3 KiB
C
88 lines
2.3 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) 2010 Fredrik Johansson
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******************************************************************************/
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#include "arith.h"
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#include "fmpz.h"
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/* note: destroys factors! */
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void
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_arith_divisor_sigma(fmpz_t res, const fmpz_factor_t factors, ulong k)
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{
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slong i;
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fmpz * p;
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fmpz_t r;
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fmpz_one(res);
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if (factors->num == 0)
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return;
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fmpz_init(r);
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if (k == 0)
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{
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for (i = 0; i < factors->num; i++)
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{
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fmpz_set_ui(r, factors->exp[i] + UWORD(1));
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fmpz_mul(res, res, r);
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}
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return;
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}
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else
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{
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for (i = 0; i < factors->num; i++)
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{
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p = factors->p + i;
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fmpz_set(p, factors->p + i);
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fmpz_pow_ui(p, p, k);
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fmpz_pow_ui(r, p, factors->exp[i] + UWORD(1));
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fmpz_sub_ui(r, r, UWORD(1));
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fmpz_sub_ui(p, p, UWORD(1));
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fmpz_divexact(p, r, p);
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}
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_fmpz_vec_prod(res, factors->p, factors->num);
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}
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fmpz_clear(r);
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}
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void
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arith_divisor_sigma(fmpz_t res, const fmpz_t n, ulong k)
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{
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fmpz_factor_t factors;
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if (fmpz_is_zero(n))
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{
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fmpz_zero(res);
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return;
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}
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fmpz_factor_init(factors);
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fmpz_factor(factors, n);
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_arith_divisor_sigma(res, factors, k);
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fmpz_factor_clear(factors);
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}
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