arb/fmpz_holonomic/seq_reverse.c

55 lines
1.8 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) 2012 Fredrik Johansson
******************************************************************************/
#include "fmpz_holonomic.h"
void
fmpz_holonomic_seq_reverse(fmpz_holonomic_t res, const fmpz_holonomic_t op)
{
long i, j, r;
r = fmpz_holonomic_order(op);
fmpz_holonomic_set(res, op);
if (r > 0)
{
fmpz c = r;
for (i = 0; i <= r; i++)
for (j = 1; j < fmpz_poly_length(res->coeffs + i); j += 2)
fmpz_neg((res->coeffs + i)->coeffs + j,
(res->coeffs + i)->coeffs + j);
for (i = 0; i <= r; i++)
fmpz_poly_taylor_shift(res->coeffs + i, res->coeffs + i, &c);
for (i = 0; i <= r / 2; i++)
fmpz_poly_swap(res->coeffs + i, res->coeffs + r - i);
fmpz_holonomic_normalise_sign(res);
}
}