FA-65224 / Epidemic compartment models / Member archive

SIR with Erlang-distributed infectious period: stage exit rate · case 04

The mean infectious period becomes k times too long.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

Infectious period split into k sequential stages each left at rate k*gamma; seeds start in stage 1; all stages transmit; Euler with dt=0.1 (10 substeps/day); return [total I at day ends including day 0 rounded 3, R rounded 3], None for k<1.

Why this case matters

Compartmental epidemic calculations drive outbreak forecasts, vaccine targets and hospital planning; a single wrong flow, rate conversion or boundary silently changes every downstream number.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: many stages	`[[20.0, 35.16, 60.953, 103.203, 168.258], 0.207]`	`[[20.0, 34.937, 55.691, 80.709, 110.985], 33.142]`	Failed

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