131 lines
4.0 KiB
C
131 lines
4.0 KiB
C
/*=============================================================================
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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) 2007 David Howden
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Copyright (C) 2007, 2008, 2009, 2010 William Hart
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Copyright (C) 2008 Richard Howell-Peak
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Copyright (C) 2011 Fredrik Johansson
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Copyright (C) 2012 Lina Kulakova
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Copyright (C) 2013 Mike Hansen
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******************************************************************************/
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#ifdef T
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#include "templates.h"
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#include "ulong_extras.h"
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int
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TEMPLATE(T, poly_factor_equal_deg_prob) (TEMPLATE(T, poly_t) factor,
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flint_rand_t state,
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const TEMPLATE(T, poly_t) pol,
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slong d,
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const TEMPLATE(T, ctx_t) ctx)
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{
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TEMPLATE(T, poly_t) a, b, c, polinv;
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TEMPLATE(T, t) t;
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fmpz_t exp, q;
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int res = 1;
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slong i, k;
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if (pol->length <= 1)
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{
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TEMPLATE_PRINTF("Exception (%s_poly_factor_equal_deg_prob): \n", T);
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flint_printf("Input polynomial is linear.\n");
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abort();
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}
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fmpz_init(q);
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TEMPLATE(T, ctx_order) (q, ctx);
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TEMPLATE(T, poly_init) (a, ctx);
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do
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{
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TEMPLATE(T, poly_randtest) (a, state, pol->length - 1, ctx);
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} while (a->length <= 1);
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TEMPLATE(T, poly_gcd) (factor, a, pol, ctx);
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if (factor->length != 1)
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{
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TEMPLATE(T, poly_clear) (a, ctx);
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return 1;
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}
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TEMPLATE(T, poly_init) (b, ctx);
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TEMPLATE(T, poly_init) (polinv, ctx);
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TEMPLATE(T, poly_reverse) (polinv, pol, pol->length, ctx);
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TEMPLATE(T, poly_inv_series_newton) (polinv, polinv, polinv->length, ctx);
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fmpz_init(exp);
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if (fmpz_cmp_ui(TEMPLATE(T, ctx_prime) (ctx), 2) > 0)
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{
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/* compute a^{(q^d-1)/2} rem pol */
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fmpz_pow_ui(exp, q, d);
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fmpz_sub_ui(exp, exp, 1);
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fmpz_fdiv_q_2exp(exp, exp, 1);
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TEMPLATE(T, poly_powmod_fmpz_sliding_preinv) (b, a, exp, 0, pol,
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polinv, ctx);
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}
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else
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{
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/* compute b = (a^{2^{k*d-1}}+a^{2^{k*d-2}}+...+a^4+a^2+a) rem pol */
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k = d * TEMPLATE(T, ctx_degree) (ctx); /* TODO: Handle overflow? */
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TEMPLATE(T, poly_rem) (b, a, pol, ctx);
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TEMPLATE(T, poly_init) (c, ctx);
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TEMPLATE(T, poly_set) (c, b, ctx);
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for (i = 1; i < k; i++)
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{
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/* c = a^{2^i} = (a^{2^{i-1}})^2 */
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TEMPLATE(T, poly_powmod_ui_binexp_preinv) (c, c, 2, pol, polinv,
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ctx);
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TEMPLATE(T, poly_add) (b, b, c, ctx);
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}
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TEMPLATE(T, poly_rem) (b, b, pol, ctx);
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TEMPLATE(T, poly_clear) (c, ctx);
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}
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fmpz_clear(exp);
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TEMPLATE(T, init) (t, ctx);
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TEMPLATE(T, sub_one) (t, b->coeffs + 0, ctx);
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TEMPLATE(T, poly_set_coeff) (b, 0, t, ctx);
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TEMPLATE(T, clear) (t, ctx);
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TEMPLATE(T, poly_gcd) (factor, b, pol, ctx);
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if ((factor->length <= 1) || (factor->length == pol->length))
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res = 0;
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TEMPLATE(T, poly_clear) (a, ctx);
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TEMPLATE(T, poly_clear) (b, ctx);
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TEMPLATE(T, poly_clear) (polinv, ctx);
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fmpz_clear(q);
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return res;
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}
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#endif
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