FA-65465 / Ecological population dynamics / Member archive

Leslie matrix projection with optional plus group: plus group retention · case 05

The plus group loses all incoming recruits from the previous class.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Births new[0] = sum f_i*n_i; survivors new[i+1] = s_i*n_i; with plus_group the last class also retains s_last*n_last; ratio is total(t)/total(t-1) of the final year (None if the previous total was 0 or no years); return [final vector rounded 4, total rounded 4, ratio rounded 6].

Why this case matters

Population projections set harvest quotas, conservation status and pest-control timing; a wrong update order, boundary or rate conversion silently changes management advice.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression: plus group fish	`[[69.46, 40.6, 16.384], 126.444, 0.796849]`	`[[322.9, 139.0, 171.16], 633.06, 1.221652]`	Failed

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