124 lines
3.3 KiB
C
124 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) 2010 Sebastian Pancratz
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******************************************************************************/
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#include <stdlib.h>
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#include <gmp.h>
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#include "flint.h"
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#include "fmpz.h"
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#include "fmpz_vec.h"
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#include "fmpz_poly.h"
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void
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_fmpz_poly_pow_multinomial(fmpz * res, const fmpz * poly, slong len, ulong e)
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{
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slong k, low, rlen;
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fmpz_t d, t;
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fmpz * P;
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rlen = (slong) e * (len - WORD(1)) + WORD(1);
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_fmpz_vec_zero(res, rlen);
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for (low = WORD(0); poly[low] == WORD(0); low++) ;
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if (low == WORD(0))
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{
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P = (fmpz *) poly;
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}
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else
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{
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P = (fmpz *) poly + low;
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len -= low;
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res += (slong) e * low;
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rlen -= (slong) e * low;
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}
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fmpz_init(d);
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fmpz_init(t);
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fmpz_pow_ui(res, P, e);
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for (k = 1; k < rlen; k++)
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{
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slong i, u = -k;
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for (i = 1; i <= FLINT_MIN(k, len - 1); i++)
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{
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fmpz_mul(t, P + i, res + (k - i));
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u += (slong) e + 1;
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if (u >= 0)
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fmpz_addmul_ui(res + k, t, (ulong) u);
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else
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fmpz_submul_ui(res + k, t, - ((ulong) u));
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}
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fmpz_add(d, d, P);
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fmpz_divexact(res + k, res + k, d);
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}
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fmpz_clear(d);
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fmpz_clear(t);
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}
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void
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fmpz_poly_pow_multinomial(fmpz_poly_t res, const fmpz_poly_t poly, ulong e)
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{
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const slong len = poly->length;
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slong rlen;
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if ((len < 2) | (e < UWORD(3)))
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{
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if (e == UWORD(0))
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fmpz_poly_set_ui(res, 1);
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else if (len == 0)
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fmpz_poly_zero(res);
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else if (len == 1)
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{
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fmpz_poly_fit_length(res, 1);
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fmpz_pow_ui(res->coeffs, poly->coeffs, e);
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_fmpz_poly_set_length(res, 1);
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}
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else if (e == UWORD(1))
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fmpz_poly_set(res, poly);
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else /* e == UWORD(2) */
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fmpz_poly_sqr(res, poly);
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return;
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}
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rlen = (slong) e * (len - 1) + 1;
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if (res != poly)
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{
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fmpz_poly_fit_length(res, rlen);
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_fmpz_poly_pow_multinomial(res->coeffs, poly->coeffs, len, e);
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_fmpz_poly_set_length(res, rlen);
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}
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else
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{
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fmpz_poly_t t;
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fmpz_poly_init2(t, rlen);
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_fmpz_poly_pow_multinomial(t->coeffs, poly->coeffs, len, e);
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_fmpz_poly_set_length(t, rlen);
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fmpz_poly_swap(res, t);
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fmpz_poly_clear(t);
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}
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}
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