FA-65152 / Epidemic compartment models / Member archive

Epidemic growth rate, doubling time and R: declining doubling time · case 02

Declining epidemics report a negative doubling time.

Member previewVariant 2 · 3 implementations · 7 checks per implementation

Case contract

r is the least-squares slope of ln(count) against day index over days with positive counts (original day indices kept); doubling time ln2/r only when r>0 else None; latent time Tl=latent_fraction*Tg, infectious time Ti=Tg-Tl, R=(1+r*Tl)*(1+r*Ti); return [r rounded 6, doubling rounded 4, R rounded 6]; None with fewer than two positive days.

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: declining	`[-0.246645, -2.8103, 0.217822]`	`[-0.246645, null, 0.217822]`	Failed

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