In contrast, time-dependent applications necessarily involve a partial differential equation (PDE). Since, as mentioned, x(C, t) (e.g., for the one-dimensional case) is the sought-for PDE solution, it is in principle necessary to impose both initial conditions and boundary conditions [i.e., x(t) at both C-grid edges] in order to solve the requisite PDE. The problem is that the boundary conditions are not known a priori. Here, we find a noteworthy disadvantage, in comparison with wave-based PDE solutions for which zero Dirichlet boundary conditions may almost always be presumed. In practice, we find that trajectory dynamics in the interior are not sensitively dependent on the choice of boundary conditions, provided the grid interval is sufficiently large, as might be expected. On the other hand, the quantum trajectory dynamics can in many cases become numerically unstable, if there is a scattering potential present. This tends to manifest as errors propagating in from the grid edges, however, rather than originating from nodes-i.e., this is not the node problem.