pqc/external/flint-2.4.3/fmpz_poly_q/scalar_div_si.c
2014-05-24 23:16:06 +02:00

105 lines
2.8 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) 2010, 2011 Sebastian Pancratz
******************************************************************************/
#include "fmpz_poly_q.h"
void fmpz_poly_q_scalar_div_si(fmpz_poly_q_t rop, const fmpz_poly_q_t op, slong x)
{
fmpz_t cont, fx, gcd;
if (FLINT_ABS(x) <= 1)
{
if (x == 0)
{
flint_printf("Exception (fmpz_poly_q_scalar_div_si). Division by zero.\n");
abort();
}
if (x == 1)
fmpz_poly_q_set(rop, op);
else
fmpz_poly_q_neg(rop, op);
return;
}
if (fmpz_poly_q_is_zero(op))
{
fmpz_poly_q_zero(rop);
return;
}
fmpz_init(cont);
fmpz_poly_content(cont, op->num);
if (fmpz_is_one(cont))
{
if (x > 0)
{
fmpz_poly_set(rop->num, op->num);
fmpz_poly_scalar_mul_si(rop->den, op->den, x);
}
else
{
fmpz_poly_neg(rop->num, op->num);
fmpz_poly_scalar_mul_ui(rop->den, op->den, - ((ulong) x));
}
fmpz_clear(cont);
return;
}
fmpz_init(fx);
fmpz_init(gcd);
fmpz_set_si(fx, x);
fmpz_gcd(gcd, cont, fx);
if (fmpz_is_one(gcd))
{
if (x > 0)
{
fmpz_poly_set(rop->num, op->num);
fmpz_poly_scalar_mul_si(rop->den, op->den, x);
}
else
{
fmpz_poly_neg(rop->num, op->num);
fmpz_poly_scalar_mul_ui(rop->den, op->den, - ((ulong) x));
}
}
else
{
fmpz_poly_scalar_divexact_fmpz(rop->num, op->num, gcd);
fmpz_divexact(fx, fx, gcd);
fmpz_poly_scalar_mul_fmpz(rop->den, op->den, fx);
if (x < 0)
{
fmpz_poly_neg(rop->num, rop->num);
fmpz_poly_neg(rop->den, rop->den);
}
}
fmpz_clear(cont);
fmpz_clear(fx);
fmpz_clear(gcd);
}