Magnitude of the radial acceleration in the plane of the disk, |a_R|, due to the bulge alone in Newtonian gravity: spherical bulge (red) and triaxial bulge (blue). For the triaxial bulge, the acceleration varies with the azimuthal angle, ϕ, which is the angle with respect to the x axis in the plane of the disk. We show the results for various values of ϕ; ϕ = 0° and ϕ = 90° correspond to the x and y axes, respectively.