Potential and forces for the Hernquist models. From left to right: the input density model is spherical, oblate, prolate, and triaxial, respectively. In each panel, the black line is the result for the model given by Merritt & Fridman (1996). The red, blue, and green lines are the results for the HO method with (n_max, l_max) = (16,12), (12,12), and (6,4), respectively. From top to bottom: the radius r was measured along the x-, x-, y-, and z-axes, respectively. The x-axis is the major axis and the z-axis is the minor axis of the density distribution.