@public
def cofactors(f, g, *gens, **args):
    """
    Compute GCD and cofactors of ``f`` and ``g``.

    Returns polynomials ``(h, cff, cfg)`` such that ``h = gcd(f, g)``, and
    ``cff = quo(f, h)`` and ``cfg = quo(g, h)`` are, so called, cofactors
    of ``f`` and ``g``.

    Examples
    ========

    >>> from sympy import cofactors
    >>> from sympy.abc import x

    >>> cofactors(x**2 - 1, x**2 - 3*x + 2)
    (x - 1, x + 1, x - 2)

    """
    options.allowed_flags(args, ['polys'])

    try:
        (F, G), opt = parallel_poly_from_expr((f, g), *gens, **args)
    except PolificationFailed as exc:
        domain, (a, b) = construct_domain(exc.exprs)

        try:
            h, cff, cfg = domain.cofactors(a, b)
        except __HOLE__:
            raise ComputationFailed('cofactors', 2, exc)
        else:
            return domain.to_sympy(h), domain.to_sympy(cff), domain.to_sympy(cfg)

    h, cff, cfg = F.cofactors(G)

    if not opt.polys:
        return h.as_expr(), cff.as_expr(), cfg.as_expr()
    else:
        return h, cff, cfg
dataset/ETHPy150Open sympy/sympy/sympy/polys/polytools.py/cofactors