Illustration of the limitations of the Singlepoly algorithm. For this analysis, five lens configurations were selected with separations between 0.2 and 1.2, and the mass ratio parameters were varied keeping m₃ < m₂ < m₁. For each configuration five source trajectories were tested, and the success rate of the Singlepoly algorithm was evaluated. The figure clearly shows that the Singlepoly algorithm fails when both mass ratios are on the order of 10⁻⁴ or lower.