111 lines
3.3 KiB
C
111 lines
3.3 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) 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 "math.h"
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int
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TEMPLATE(T, poly_is_irreducible_ben_or) (const TEMPLATE(T, poly_t) f,
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const TEMPLATE(T, ctx_t) ctx)
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{
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int result;
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slong i, n;
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fmpz_t q;
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TEMPLATE(T, poly_t) g, x, xq, xqimx;
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TEMPLATE(T, poly_t) v, vinv;
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n = TEMPLATE(T, poly_degree) (f, ctx);
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if (n < 2)
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return 1;
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if (!TEMPLATE(T, poly_is_squarefree) (f, ctx))
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return 0;
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TEMPLATE(T, poly_init) (v, ctx);
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TEMPLATE(T, poly_init) (vinv, ctx);
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TEMPLATE(T, poly_make_monic) (v, f, ctx);
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TEMPLATE(T, poly_reverse) (vinv, v, v->length, ctx);
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TEMPLATE(T, poly_inv_series_newton) (vinv, vinv, v->length, ctx);
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TEMPLATE(T, poly_init) (x, ctx);
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TEMPLATE(T, poly_init) (xq, ctx);
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TEMPLATE(T, poly_init) (xqimx, ctx);
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/* Compute xq = x^q mod f */
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fmpz_init(q);
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fmpz_pow_ui(q, TEMPLATE(T, ctx_prime) (ctx),
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TEMPLATE(T, ctx_degree) (ctx));
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TEMPLATE(T, poly_gen) (x, ctx);
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TEMPLATE(T, poly_powmod_fmpz_sliding_preinv) (xq, x, q, 0, v, vinv, ctx);
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TEMPLATE(T, poly_set) (xqimx, xq, ctx);
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result = 1;
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TEMPLATE(T, poly_init) (g, ctx);
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for (i = 1; i <= n / 2; i++)
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{
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TEMPLATE(T, poly_sub) (xqimx, xqimx, x, ctx);
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TEMPLATE(T, poly_gcd) (g, f, xqimx, ctx);
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if (!TEMPLATE(T, poly_is_one) (g, ctx))
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{
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result = 0;
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break;
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}
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else if (i == n / 2)
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{
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/* We don't need to compute the last step */
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break;
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}
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TEMPLATE(T, poly_add) (xqimx, xqimx, x, ctx);
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if (TEMPLATE(CAP_T, POLY_ITERATED_FROBENIUS_CUTOFF) (ctx, v->length))
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{
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TEMPLATE(T, poly_powmod_fmpz_sliding_preinv) (xqimx, xqimx, q, 0,
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v, vinv, ctx);
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}
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else
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{
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TEMPLATE(T, poly_compose_mod_preinv) (xqimx, xqimx, xq, v, vinv,
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ctx);
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}
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}
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TEMPLATE(T, poly_clear) (xq, ctx);
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TEMPLATE(T, poly_clear) (xqimx, ctx);
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TEMPLATE(T, poly_clear) (v, ctx);
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TEMPLATE(T, poly_clear) (vinv, ctx);
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fmpz_clear(q);
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return result;
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}
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#endif
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