60 lines
1.9 KiB
C
60 lines
1.9 KiB
C
/*=============================================================================
|
|
|
|
This file is part of FLINT.
|
|
|
|
FLINT 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.
|
|
|
|
FLINT 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 FLINT; if not, write to the Free Software
|
|
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
|
|
|
|
=============================================================================*/
|
|
/******************************************************************************
|
|
|
|
Copyright (C) 2009 William Hart
|
|
|
|
******************************************************************************/
|
|
|
|
#include <gmp.h>
|
|
#include "flint.h"
|
|
#include "ulong_extras.h"
|
|
#include "fmpz.h"
|
|
|
|
void
|
|
fmpz_submul(fmpz_t f, const fmpz_t g, const fmpz_t h)
|
|
{
|
|
fmpz c1 = *g;
|
|
if (!COEFF_IS_MPZ(c1)) /* g is small */
|
|
{
|
|
if (c1 < WORD(0))
|
|
fmpz_addmul_ui(f, h, -c1);
|
|
else
|
|
fmpz_submul_ui(f, h, c1);
|
|
}
|
|
else
|
|
{
|
|
fmpz c2 = *h;
|
|
if (!COEFF_IS_MPZ(c2)) /* h is small */
|
|
{
|
|
if (c2 < WORD(0))
|
|
fmpz_addmul_ui(f, g, -c2);
|
|
else
|
|
fmpz_submul_ui(f, g, c2);
|
|
}
|
|
else /* both g and h are large */
|
|
{
|
|
__mpz_struct *mpz_ptr = _fmpz_promote_val(f);
|
|
mpz_submul(mpz_ptr, COEFF_TO_PTR(c1), COEFF_TO_PTR(c2));
|
|
_fmpz_demote_val(f); /* cancellation may have occurred */
|
|
}
|
|
}
|
|
}
|