center of mass. The node is sufficiently far away when this ratio is smaller than a threshold value θ. The parameter θ determines the accuracy of the simulation; larger values of θ increase the speed of the simulation but decreases its accuracy. If θ = 0, no internal node is treated as a single body and the algorithm degenerates to a direct-sum algorithm. See also NEMO (Stellar Dynamics Toolbox) Nearest neighbor search Fast multipole method References and sources References Sources External links Treecodes, J. Barnes Parallel TreeCode HTML5/JavaScript Example Graphical Barnes–Hut Simulation PEPC – The Pretty Efficient Parallel Coulomb solver, an open-source parallel Barnes–Hut tree code with exchangeable interaction kernel for a multitude of applications Parallel GPU N-body simulation program with fast stackless particles tree traversal Barnes-Hut galaxy simulator at beltoforion.de Simulation Gravity Physical cosmology Numerical integration (quadrature) Articles containing video clips