It Pays to Be Lazy: Reusing Force Approximations to Compute Better Graph Layouts Faster

N-body simulations are common in applications ranging from physics simulations to computing graph layouts. The simulations are slow, but tree-based approximation algorithms like Barnes-Hut or the Fast Multipole Method dramatically improve performance. This paper proposes two new update schedules, uniform and dynamic, to make this type of approximation algorithm even faster by updating the approximation less often. An evaluation of these new schedules on computing graph layouts finds that the schedules typically decrease the running time by 9% to 18% for Barnes-Hut and 88% to 92% for the Fast Multipole Method. An experiment using 4 layout quality metrics on 50 graphs shows that the uniform schedule has similar or better graph layout quality compared to the standard BarnesHut or Fast Multipole Method algorithms.