89 lines
2.4 KiB
C
89 lines
2.4 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) 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 "fmpz.h"
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#include "fmpz_poly.h"
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void
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_fmpz_poly_revert_series(fmpz * Qinv, const fmpz * Q, slong n)
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{
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_fmpz_poly_revert_series_lagrange_fast(Qinv, Q, n);
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}
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void
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fmpz_poly_revert_series(fmpz_poly_t Qinv, const fmpz_poly_t Q, slong n)
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{
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fmpz *Qcopy;
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int Qalloc;
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slong Qlen = Q->length;
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if (Qlen < 2 || !fmpz_is_zero(Q->coeffs) || !fmpz_is_pm1(Q->coeffs + 1))
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{
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flint_printf("Exception (fmpz_poly_revert_series). Input must have \n"
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"zero constant term and +1 or -1 as coefficient of x^1\n.");
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abort();
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}
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if (Qlen >= n)
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{
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Qcopy = Q->coeffs;
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Qalloc = 0;
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}
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else
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{
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slong i;
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Qcopy = (fmpz *) flint_malloc(n * sizeof(fmpz));
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for (i = 0; i < Qlen; i++)
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Qcopy[i] = Q->coeffs[i];
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for ( ; i < n; i++)
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Qcopy[i] = 0;
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Qalloc = 1;
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}
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if (Qinv != Q)
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{
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fmpz_poly_fit_length(Qinv, n);
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_fmpz_poly_revert_series(Qinv->coeffs, Qcopy, n);
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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, n);
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_fmpz_poly_revert_series(t->coeffs, Qcopy, n);
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fmpz_poly_swap(Qinv, t);
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fmpz_poly_clear(t);
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}
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_fmpz_poly_set_length(Qinv, n);
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_fmpz_poly_normalise(Qinv);
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if (Qalloc)
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flint_free(Qcopy);
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}
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