'Computes the subresultant PRS of ``f`` and ``g``.
Examples
>>> from sympy import Poly
>>> from sympy.abc import x
>>> Poly(x**2 + 1, x).subresultants(Poly(x**2 - 1, x))
[Poly(x**2 + 1, x, domain=\'ZZ\'),
Poly(x**2 - 1, x, domain=\'ZZ\'),
Poly(-2, x, domain=\'ZZ\')]'

def subresultants(f, g):

    (_, per, F, G) = f._unify(g)
    if hasattr(f.rep, 'subresultants'):
        result = F.subresultants(G)
    else:
        raise OperationNotSupported(f, 'subresultants')
    return list(map(per, result))
