97 lines
2.6 KiB
C
97 lines
2.6 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 "fmpq.h"
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#include "fmpz_mat.h"
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void
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_fmpq_set_cfrac_basecase(fmpz_t p, fmpz_t t, fmpz_t q, fmpz_t u,
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const fmpz * c, slong n)
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{
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slong i;
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fmpz_set(p, c);
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fmpz_one(q);
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fmpz_one(t);
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fmpz_zero(u);
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for (i = 1; i < n; i++)
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{
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fmpz_addmul(t, c + i, p);
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fmpz_addmul(u, c + i, q);
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fmpz_swap(t, p);
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fmpz_swap(u, q);
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}
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}
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void
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_fmpq_set_cfrac_divconquer(fmpz_mat_t P, const fmpz * c, slong n)
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{
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if (n < 32)
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{
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_fmpq_set_cfrac_basecase(
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fmpz_mat_entry(P, 0, 0), fmpz_mat_entry(P, 0, 1),
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fmpz_mat_entry(P, 1, 0), fmpz_mat_entry(P, 1, 1), c, n);
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}
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else
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{
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fmpz_mat_t L, R;
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slong m = n / 2;
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fmpz_mat_init(L, 2, 2);
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fmpz_mat_init(R, 2, 2);
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_fmpq_set_cfrac_divconquer(L, c, m);
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_fmpq_set_cfrac_divconquer(R, c + m, n - m);
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fmpz_mat_mul_classical(P, L, R); /* Should be Strassen */
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fmpz_mat_clear(L);
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fmpz_mat_clear(R);
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}
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}
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void
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fmpq_set_cfrac(fmpq_t x, const fmpz * c, slong n)
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{
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if (n <= 64)
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{
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fmpz_t t, u;
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fmpz_init(t);
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fmpz_init(u);
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_fmpq_set_cfrac_basecase(fmpq_numref(x), t, fmpq_denref(x), u, c, n);
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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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fmpz_mat_t P;
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fmpz_mat_init(P, 2, 2);
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_fmpq_set_cfrac_divconquer(P, c, n);
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fmpz_set(fmpq_numref(x), fmpz_mat_entry(P, 0, 0));
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fmpz_set(fmpq_denref(x), fmpz_mat_entry(P, 1, 0));
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fmpz_mat_clear(P);
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}
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}
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