arb/arb_poly/mullow.c
2015-11-05 17:59:29 +00:00

83 lines
2.5 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 "arb_poly.h"
#define BLOCK_CUTOFF 16
void
_arb_poly_mullow(arb_ptr res,
arb_srcptr poly1, slong len1,
arb_srcptr poly2, slong len2, slong n, slong prec)
{
if (n == 1)
{
arb_mul(res, poly1, poly2, prec);
}
else
{
if (n < BLOCK_CUTOFF || len1 < BLOCK_CUTOFF || len2 < BLOCK_CUTOFF)
_arb_poly_mullow_classical(res, poly1, len1, poly2, len2, n, prec);
else
_arb_poly_mullow_block(res, poly1, len1, poly2, len2, n, prec);
}
}
void
arb_poly_mullow(arb_poly_t res, const arb_poly_t poly1,
const arb_poly_t poly2,
slong n, slong prec)
{
slong len_out;
if (poly1->length == 0 || poly2->length == 0 || n == 0)
{
arb_poly_zero(res);
return;
}
len_out = poly1->length + poly2->length - 1;
if (n > len_out)
n = len_out;
if (res == poly1 || res == poly2)
{
arb_poly_t t;
arb_poly_init2(t, n);
_arb_poly_mullow(t->coeffs, poly1->coeffs, poly1->length,
poly2->coeffs, poly2->length, n, prec);
arb_poly_swap(res, t);
arb_poly_clear(t);
}
else
{
arb_poly_fit_length(res, n);
_arb_poly_mullow(res->coeffs, poly1->coeffs, poly1->length,
poly2->coeffs, poly2->length, n, prec);
}
_arb_poly_set_length(res, n);
_arb_poly_normalise(res);
}