“…2D boundary-value problems of this theory are studied, as a rule, using several popular methods, such as the Rayleigh method and its modern versions [13][14][15][16], the Fourier modal method and the C-method [6,8,10,17], rigorous coupled-wave methods and cross-section methods (differential methods) [8,9], finite-element methods [18], and analytical regularization methods [6,[10][11][12]. The advantages and disadvantages of these frequency-domain methods are well known.…”