Trajectory of the torus angular-momentum vector in the x-y plane when the accretion torque evolves exponentially from zero to τ_f = −1 for various cases. A torus that is initially precessing with an angular momentum L(0) = − 0.3i approaches the final state of precession about the new equilibrium point, iτ_f/ω_p, slowly or rapidly for a low (ω_h = 0.2ω_p) or high (ω_h = 2ω_p) healing frequency, as in the left and middle panels, respectively. The right panel presents the same case as in the left panel (i.e., ω_h = 0.2ω_p), except that initially the torus has a zero angular momentum projection onto the x-y plane, i.e., L(0) = 0, highlighting that a change in accretion torque can induce precession in a torus. In all three examples, we set ω_p = 1 and the phase evolution is represented by both the color and the decreasing thickness of the curve.