Hierarchical N-body solver

Fast Multipole Gravity Lab

Many bodies. One hierarchical gravitational field.

M2M → M2L → L2L → P2P

Experiment controls FMM / 2D

Scene 01

Particle count1,024

1288,192

Expansion order3

Separation ratio1.60

Leaf capacity32

Higher orders and wider separation improve accuracy, at a greater cost per step.

Gravity G0.65

Softening ε0.018

Timestep Δt0.0030

Particle trails Quadtree overlay Acceleration vectors Automatic sampled error

Up to 24 forces checked every 25 steps. Larger scenes (up to 8,192) may run more slowly.

Inside the solver

INITIAL CONDITION / 01Spiral galaxy

A rotating stellar disk around a massive core.

Click to inject a particle cloud · Shift-click to add a massive body · Space pauses