Effect of the number of bins per component N on the wall-clock time T (the top panels), the L₂ error ε₂ (the middle panels), and the relative error of the total mass ΔM (the bottom panels) for the constant time step. From the left, the panels show the results for the (a) one-component constant kernel, (b) one-component additive kernel, (c) two-component constant kernel, and (d) two-component additive kernel. In each plot, different colors correspond to the direct method, or the different values of θ_c for the tree methods. All tree method cases were calculated with k_c = 1 000 000. For the wall-clock time T, the lines were fit by the least squares method, using the logarithmic values of N and T.