Discrete complex image method with spatial error criterion and automatic order selection

In this paper a spatial-domain weighted error metric is proposed and its mapping to the spectral domain is derived. It is observed that the weighted error-energy minimization in the spectral domain becomes equivalent to the one in the spatial domain. In addition, with the use of the spatial-domain error criterion, an automatic order selection method is proposed to determine the number of exponentials. Typically, the number of exponentials used to express the spectral-domain Green's functions is designated by the number of the dominant eigenvalues of a selection matrix in the subspace method, and these eigenvalues are selected manually or by the computer based on a predefined tolerance, that is, user intervention is needed in either case.