126 lines
3.0 KiB
C
126 lines
3.0 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) 2012 Sebastian Pancratz
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******************************************************************************/
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#include <gmp.h>
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#include "flint.h"
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#include "fmpz.h"
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#include "padic.h"
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#include "ulong_extras.h"
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void _padic_log_satoh(fmpz_t z, const fmpz_t y, slong v, const fmpz_t p, slong N)
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{
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if (N < 16)
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{
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_padic_log_rectangular(z, y, v, p, N);
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}
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else
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{
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const slong k = n_sqrt(N);
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fmpz_t t, pk, pNk;
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fmpz_init(t);
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fmpz_init(pk);
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fmpz_init(pNk);
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fmpz_pow_ui(pk, p, k);
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fmpz_pow_ui(pNk, p, N + k);
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fmpz_sub_ui(t, y, 1);
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fmpz_neg(t, t);
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fmpz_powm(t, t, pk, pNk);
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fmpz_sub_ui(t, t, 1);
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fmpz_neg(t, t);
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/* TODO: Improve suggested valuation */
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_padic_log_rectangular(z, t, k + 1, p, N + k);
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fmpz_divexact(z, z, pk);
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fmpz_clear(t);
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fmpz_clear(pk);
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fmpz_clear(pNk);
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}
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}
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int padic_log_satoh(padic_t rop, const padic_t op, const padic_ctx_t ctx)
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{
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const fmpz *p = ctx->p;
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const slong N = padic_prec(rop);
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if (padic_val(op) < 0)
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{
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return 0;
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}
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else
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{
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fmpz_t y;
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int ans;
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fmpz_init(y);
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padic_get_fmpz(y, op, ctx);
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fmpz_sub_ui(y, y, 1);
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fmpz_neg(y, y);
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if (fmpz_is_zero(y))
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{
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padic_zero(rop);
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ans = 1;
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}
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else
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{
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fmpz_t t;
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slong v;
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fmpz_init(t);
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v = fmpz_remove(t, y, ctx->p);
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fmpz_clear(t);
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if (v >= 2 || (!fmpz_equal_ui(p, 2) && v >= 1))
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{
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if (v >= N)
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{
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padic_zero(rop);
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}
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else
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{
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_padic_log_satoh(padic_unit(rop), y, v, p, N);
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padic_val(rop) = 0;
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padic_reduce(rop, ctx);
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}
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ans = 1;
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}
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else
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{
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ans = 0;
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}
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}
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fmpz_clear(y);
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return ans;
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}
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}
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