105 lines
3.1 KiB
C
105 lines
3.1 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) 2010 Sebastian Pancratz
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Copyright (C) 2010 William Hart
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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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void
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_nmod_poly_pow_trunc(mp_ptr res, mp_srcptr poly,
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ulong e, slong trunc, nmod_t mod)
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{
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_nmod_poly_pow_trunc_binexp(res, poly, e, trunc, mod);
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}
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void
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nmod_poly_pow_trunc(nmod_poly_t res,
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const nmod_poly_t poly, ulong e, slong trunc)
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{
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const slong len = poly->length;
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mp_ptr p;
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int pcopy = 0;
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if (len < 2 || e < UWORD(3) || trunc == 0)
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{
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if (len == 0 || trunc == 0)
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nmod_poly_zero(res);
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else if (len == 1)
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{
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nmod_poly_fit_length(res, 1);
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res->coeffs[0] = n_powmod2_ui_preinv(poly->coeffs[0], e,
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poly->mod.n, poly->mod.ninv);
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res->length = 1;
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_nmod_poly_normalise(res);
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}
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else if (e == UWORD(0))
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{
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nmod_poly_set_coeff_ui(res, 0, UWORD(1));
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res->length = 1;
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_nmod_poly_normalise(res);
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}
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else if (e == UWORD(1))
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{
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nmod_poly_set(res, poly);
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nmod_poly_truncate(res, trunc);
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}
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else /* e == UWORD(2) */
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nmod_poly_mullow(res, poly, poly, trunc);
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return;
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}
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if (poly->length < trunc)
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{
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p = _nmod_vec_init(trunc);
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flint_mpn_copyi(p, poly->coeffs, poly->length);
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flint_mpn_zero(p + poly->length, trunc - poly->length);
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pcopy = 1;
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} else
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p = poly->coeffs;
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if (res != poly || pcopy)
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{
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nmod_poly_fit_length(res, trunc);
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_nmod_poly_pow_trunc(res->coeffs, p, e, trunc, poly->mod);
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}
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else
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{
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nmod_poly_t t;
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nmod_poly_init2(t, poly->mod.n, trunc);
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_nmod_poly_pow_trunc(t->coeffs, p, e, trunc, poly->mod);
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nmod_poly_swap(res, t);
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nmod_poly_clear(t);
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}
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if (pcopy)
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_nmod_vec_clear(p);
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res->length = trunc;
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_nmod_poly_normalise(res);
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}
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