Introduction

Spectral factorization has been recently revived by the advent of the helical coordinate system. Several methods are reported in the literature, ranging from Fourier domain methods, such as Kolmogoroff's Claerbout (1992); Kolmogoroff (1939), to iterative methods, such as the Wilson-Burg method Claerbout (1998); Sava et al. (1998); Wilson (1969).

In this paper, after reviewing the general theory of root estimation by iterative methods, we derive a general square root relationship applicable to both real numbers and to auto-correlation functions. We introduce a new spectral factorization relation and show its relation to the Wilson-Burg method.