Representation of a path (thick solid line) linking r_i = R − l/2 with r_e = R + l/2, formed by the line segments [r_ir_C], [r_Cr_A], and [r_Ar_e]. The dashed lines represent branch cuts due to the presence of the logarithms in the Frobenius solutions. In this representation, the represented disks only have radii of 80% of those of the corresponding convergence disks, as this was used in numerical calculations to avoid inaccuracy due to the slow convergence of the series near the edges of the convergence disks.