134 lines
3.3 KiB
C
134 lines
3.3 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) 2011 Fredrik Johansson
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******************************************************************************/
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#include <gmp.h>
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#include "flint.h"
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#include "nmod_vec.h"
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#include "nmod_poly.h"
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#include "ulong_extras.h"
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void
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_nmod_poly_compose_mod_horner(mp_ptr res,
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mp_srcptr f, slong lenf, mp_srcptr g, mp_srcptr h, slong lenh, nmod_t mod)
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{
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slong i, len;
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mp_ptr t;
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if (lenh == 1)
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return;
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if (lenf == 1)
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{
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res[0] = f[0];
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return;
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}
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if (lenh == 2)
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{
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res[0] = _nmod_poly_evaluate_nmod(f, lenf, g[0], mod);
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return;
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}
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len = lenh - 1;
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i = lenf - 1;
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t = _nmod_vec_init(len);
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_nmod_vec_scalar_mul_nmod(res, g, len, f[i], mod);
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i--;
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if (i >= 0)
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res[0] = nmod_add(res[0], f[i], mod);
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while (i > 0)
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{
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i--;
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_nmod_poly_mulmod(t, res, len, g, len, h, lenh, mod);
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_nmod_poly_add(res, t, len, f + i, 1, mod);
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}
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_nmod_vec_clear(t);
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}
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void
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nmod_poly_compose_mod_horner(nmod_poly_t res,
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const nmod_poly_t poly1, const nmod_poly_t poly2,
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const nmod_poly_t poly3)
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{
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slong len1 = poly1->length;
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slong len2 = poly2->length;
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slong len3 = poly3->length;
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slong len = len3 - 1;
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mp_ptr ptr2;
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if (len3 == 0)
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{
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flint_printf("Exception (nmod_poly_compose_mod_horner). Division by zero.\n");
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abort();
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}
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if (len1 == 0 || len3 == 1)
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{
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nmod_poly_zero(res);
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return;
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}
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if (len1 == 1)
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{
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nmod_poly_set(res, poly1);
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return;
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}
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if (res == poly3 || res == poly1)
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{
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nmod_poly_t tmp;
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nmod_poly_init_preinv(tmp, res->mod.n, res->mod.ninv);
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nmod_poly_compose_mod_horner(tmp, poly1, poly2, poly3);
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nmod_poly_swap(tmp, res);
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nmod_poly_clear(tmp);
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return;
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}
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ptr2 = _nmod_vec_init(len);
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if (len2 <= len)
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{
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flint_mpn_copyi(ptr2, poly2->coeffs, len2);
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flint_mpn_zero(ptr2 + len2, len - len2);
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}
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else
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{
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_nmod_poly_rem(ptr2, poly2->coeffs, len2,
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poly3->coeffs, len3, res->mod);
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}
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nmod_poly_fit_length(res, len);
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_nmod_poly_compose_mod_horner(res->coeffs,
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poly1->coeffs, len1, ptr2, poly3->coeffs, len3, res->mod);
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res->length = len;
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_nmod_poly_normalise(res);
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_nmod_vec_clear(ptr2);
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}
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