2019-11-18 07:44:36 -0500 received badge ● Student (source) 2019-11-18 07:43:03 -0500 asked a question simple script gives "ValueError: element is not in the prime field" I have a very simple script that does not work. It is the following. for a in range(1,r): for b in range(1,r): g=a+b*x^2+x^4 if g.is_irreducible(): K.=FiniteField(r^4, name='a', modulus = g) if a^l != 1: print("hooray")  Here l is defined somewhere else, but that is not what gives the error I think. I think the error occurs when sage goes over the line "K.=FiniteField(r^4, name='a', modulus = g)", because maybe the line "g=a+b*x^2+x^4" does not work? If I do this script manually without the for loops, by just assigning some values to a and b, then it works fine.