Completely normal elements in finite abelian extensions

Abstract

We give a completely normal element in the maximal real subfield of a cyclotomic field over the field of rational numbers, which is different from that of Okada. This result is a consequence of the criterion for a normal element developed in [Normal bases of ray class fields over imaginary quadratic fields, Math. Zeit.]. Furthermore, we find a completely normal element in certain extension of modular function fields in terms of a quotient of the modular discriminant function.