pub(crate) const SURPLUS_LOSS_TOLERANCE_DIVISOR: u8 = 4;Expand description
Share loss a polynomial’s surplus is sized to absorb, as a reciprocal: 1/5 is 20 %.
The surplus is insurance against lost shares, and this is the loss rate it covers. A
polynomial reconstructs from the first threshold distinct shares to arrive out of
threshold + surplus emitted, so surviving a per-packet loss rate of p needs
surplus >= threshold · p/(1−p) — which makes the surplus inherently a ratio of the
threshold, and surplus/(threshold + surplus) the loss rate it tolerates.
At threshold/4 that is 20 %, and default_surplus_for rounds up so it is a floor rather
than an approximation — see there for why the direction matters.