pub fn decay_kernel(phase: f64) -> f64Expand description
The time-decay kernel.
phase = τ / θ is how far through its expected life the move is. The
curve stays at 1 for the first 1.5 expected lifetimes and then halves
every further θ bars (0.5 at phase 2.5, 0.25 at 3.5). The shape is not a
guess: it is the measured profile of post-fire move size.