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/*
Copyright (C) 2010, 2011 Sebastian Pancratz
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "fmpz.h"
#include "fmpz_poly_q.h"
void fmpz_poly_q_inv(fmpz_poly_q_t rop, const fmpz_poly_q_t op)
{
if (fmpz_poly_is_zero(op->num))
{
flint_throw(FLINT_ERROR, "Exception (fmpz_poly_q_inv). Zero is not invertible.\n");
}
if (rop == op)
{
fmpz_poly_swap(rop->num, rop->den);
if (fmpz_sgn(fmpz_poly_lead(rop->den)) < 0)
{
fmpz_poly_neg(rop->num, rop->num);
fmpz_poly_neg(rop->den, rop->den);
}
}
else
{
if (fmpz_sgn(fmpz_poly_lead(op->num)) > 0)
{
fmpz_poly_set(rop->num, op->den);
fmpz_poly_set(rop->den, op->num);
}
else
{
fmpz_poly_neg(rop->num, op->den);
fmpz_poly_neg(rop->den, op->num);
}
}
}