arb/arb_poly/revert_series.c

66 lines
2.1 KiB
C

/*=============================================================================
This file is part of ARB.
ARB is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
ARB is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with ARB; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2013 Fredrik Johansson
******************************************************************************/
#include "arb_poly.h"
void
_arb_poly_revert_series(arb_ptr Qinv,
arb_srcptr Q, slong Qlen, slong n, slong prec)
{
_arb_poly_revert_series_lagrange_fast(Qinv, Q, Qlen, n, prec);
}
void
arb_poly_revert_series(arb_poly_t Qinv,
const arb_poly_t Q, slong n, slong prec)
{
slong Qlen = Q->length;
if (Qlen < 2 || !arb_is_zero(Q->coeffs)
|| arb_contains_zero(Q->coeffs + 1))
{
flint_printf("Exception (arb_poly_revert_series). Input must \n"
"have zero constant term and nonzero coefficient of x^1.\n");
abort();
}
if (Qinv != Q)
{
arb_poly_fit_length(Qinv, n);
_arb_poly_revert_series(Qinv->coeffs, Q->coeffs, Qlen, n, prec);
}
else
{
arb_poly_t t;
arb_poly_init2(t, n);
_arb_poly_revert_series(t->coeffs, Q->coeffs, Qlen, n, prec);
arb_poly_swap(Qinv, t);
arb_poly_clear(t);
}
_arb_poly_set_length(Qinv, n);
_arb_poly_normalise(Qinv);
}