99 lines
2.8 KiB
C
99 lines
2.8 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) 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 "ulong_extras.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_log_series(mp_ptr res, mp_srcptr f, slong n, nmod_t mod)
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{
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mp_ptr f_diff;
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mp_ptr f_inv;
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f_diff = _nmod_vec_init(n);
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f_inv = _nmod_vec_init(n);
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_nmod_poly_derivative(f_diff, f, n, mod); f_diff[n-1] = UWORD(0);
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_nmod_poly_inv_series(f_inv, f, n, mod);
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_nmod_poly_mullow(res, f_diff, n - 1, f_inv, n - 1, n - 1, mod);
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_nmod_poly_integral(res, res, n, mod);
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_nmod_vec_clear(f_diff);
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_nmod_vec_clear(f_inv);
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}
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void
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nmod_poly_log_series(nmod_poly_t res, const nmod_poly_t f, slong n)
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{
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mp_ptr f_coeffs;
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slong k;
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slong flen = f->length;
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if (flen < 1 || f->coeffs[0] != UWORD(1))
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{
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flint_printf("Exception (nmod_poly_log_series). Constant term != 1.\n");
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abort();
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}
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if (flen == 1 || n < 2)
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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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nmod_poly_fit_length(res, n);
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/* Efficiently handle monomials */
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for (k = 1; f->coeffs[k] == UWORD(0) && k < n - 1; k++);
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if (k == flen - 1 || k == n - 1)
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{
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flen = FLINT_MIN(flen, n);
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_nmod_poly_log_series_monomial_ui(res->coeffs,
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f->coeffs[flen-1], flen - 1, n, res->mod);
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}
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else
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{
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if (flen < n)
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{
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f_coeffs = _nmod_vec_init(n);
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flint_mpn_copyi(f_coeffs, f->coeffs, flen);
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flint_mpn_zero(f_coeffs + flen, n - flen);
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}
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else
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f_coeffs = f->coeffs;
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_nmod_poly_log_series(res->coeffs, f_coeffs, n, res->mod);
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if (flen < n)
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_nmod_vec_clear(f_coeffs);
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}
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res->length = n;
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_nmod_poly_normalise(res);
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}
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