If I have an algebraic number field
sage: S.<x> = NumberField(x^2+13)
is there a way to find out if an element is irreducible? There seems to be only a function to check if it is prime:
sage: (S(7)).is_prime()
False
But 7 is irreducible in $\mathbb{Q}(\sqrt{-13})$... how could I find that out?
