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/*
Copyright (C) 2010 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 "fmpq_poly.h"
void fmpq_poly_inv(fmpq_poly_t poly1, const fmpq_poly_t poly2)
{
if (poly2->length != 1)
{
flint_throw(FLINT_ERROR, "Exception (fmpq_poly_inv). poly2 is not invertible.\n");
}
if (poly1 == poly2)
{
fmpz_swap(poly1->coeffs, poly1->den);
if (fmpz_sgn(poly1->den) < 0)
{
fmpz_neg(poly1->coeffs, poly1->coeffs);
fmpz_neg(poly1->den, poly1->den);
}
}
else
{
fmpq_poly_fit_length(poly1, 1);
if (fmpz_sgn(poly2->coeffs) > 0)
{
fmpz_set(poly1->coeffs, poly2->den);
fmpz_set(poly1->den, poly2->coeffs);
}
else
{
fmpz_neg(poly1->coeffs, poly2->den);
fmpz_neg(poly1->den, poly2->coeffs);
}
_fmpq_poly_set_length(poly1, 1);
}
}