109 lines
2.9 KiB
C
109 lines
2.9 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, 2012 Sebastian Pancratz
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******************************************************************************/
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#include "fmpz_mod_poly.h"
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#include "padic_poly.h"
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void padic_poly_inv_series(padic_poly_t Qinv, const padic_poly_t Q, slong n,
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const padic_ctx_t ctx)
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{
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fmpz_t cinv;
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fmpz_t pow;
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int palloc;
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fmpz *Qcopy;
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int Qalloc;
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if (Q->length == 0 || fmpz_is_zero(Q->coeffs + 0))
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{
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flint_printf("Exception (padic_poly_inv_series): Constant term is zero.\n");
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abort();
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}
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if (fmpz_divisible(Q->coeffs + 0, ctx->p))
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{
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flint_printf("Exception (padic_poly_inv_series):\n");
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flint_printf("Valuation of constant term is not minimal.\n");
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abort();
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}
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if (- Q->val >= Qinv->N)
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{
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padic_poly_zero(Qinv);
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return;
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}
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if (Q->length >= 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 < Q->length; i++)
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Qcopy[i] = Q->coeffs[i];
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mpn_zero((mp_ptr) Qcopy + i, n - i);
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Qalloc = 1;
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}
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fmpz_init(cinv);
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fmpz_init(pow);
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_padic_inv(cinv, Q->coeffs, ctx->p, Qinv->N + Q->val);
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palloc = _padic_ctx_pow_ui(pow, Qinv->N + Q->val, ctx);
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if (Qinv != Q)
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{
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padic_poly_fit_length(Qinv, n);
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_fmpz_mod_poly_inv_series_newton(Qinv->coeffs, Qcopy, n, cinv, pow);
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}
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else
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{
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fmpz *t = _fmpz_vec_init(n);
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_fmpz_mod_poly_inv_series_newton(t, Qcopy, n, cinv, pow);
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_fmpz_vec_clear(Qinv->coeffs, Qinv->alloc);
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Qinv->coeffs = t;
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Qinv->alloc = n;
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Qinv->length = n;
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}
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Qinv->val = - Q->val;
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_padic_poly_set_length(Qinv, n);
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_padic_poly_normalise(Qinv);
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fmpz_clear(cinv);
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if (palloc)
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fmpz_clear(pow);
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if (Qalloc)
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flint_free(Qcopy);
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}
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