arb/fmpcb_poly/div_root.c

60 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) 2011 William Hart
Copyright (C) 2012 Fredrik Johansson
******************************************************************************/
#include "fmpcb_poly.h"
void
_fmpcb_poly_div_root(fmpcb_ptr Q, fmpcb_t R, fmpcb_srcptr A,
long len, const fmpcb_t c, long prec)
{
fmpcb_t r, t;
long i;
if (len < 2)
{
fmpcb_zero(R);
return;
}
fmpcb_init(r);
fmpcb_init(t);
fmpcb_set(t, A + len - 2);
fmpcb_set(Q + len - 2, A + len - 1);
fmpcb_set(r, Q + len - 2);
/* TODO: avoid the extra assignments (but still support aliasing) */
for (i = len - 2; i > 0; i--)
{
fmpcb_mul(r, r, c, prec);
fmpcb_add(r, r, t, prec);
fmpcb_set(t, A + i - 1);
fmpcb_set(Q + i - 1, r);
}
fmpcb_mul(r, r, c, prec);
fmpcb_add(R, r, t, prec);
}