Fast computation of Gauss sums and resolution of the root of unity ambiguity
An elementary approach is shown which derives the values of the Gauss sums over , p odd, of a cubic character. New links between Gauss sums over different field extensions are shown in terms of factorizations of the Gauss sums themselves, which are then revisited in terms of prime ideal decompositions. Interestingly, one of these results gives a representation of primes p of the form 6k+1 by a binary quadratic form in integers of a subfield of the cyclotomic field of the pth roots of unity.
By an elementary approach, we derive the value of the Gauss sum of a cubic character over a finite field without using Davenport-Hasse’s theorem (namely, if s is odd the Gauss sum is -1, and if s is even its value is ).