Multiplicative character theory provides a natural setting for developing the complexity results of Auslander-Feig- Winograd . The first reason for this is the simplicity of the formulas describing the action of FT on multiplicative characters. We will now discuss a second important property of multiplicative characters. In a sense defined below, the spaces spanned by the subsets V k , 1 ≤ k > m, of multiplicative characters are rational subspaces. As a consequence, we will be able to rationally manipulate the FT matrix F(p m ) into block diagonal matrices where each block action corresponds to some polynomial multiplication modulo a rational polynomial of a special kind. This is the main result in the work of Auslander-Feig-Winograd. Details from the point of view of multiplicative character theory can be found in .
KeywordsRational Basis Discrete Fourier Transform Unit Group Basis Versus Rational Vector
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- Winograd, S. Arithmetic Complexity of Computations, CBMS Regional Conf. Ser. in Math. Vol. 33, Soc. Indus. Appl. Math., Philadelphia, 1980.Google Scholar