FA-65403 / Ecological population dynamics / Member archive

Beverton-Holt recruitment convergence: initial state check · case 03

A stock that starts at equilibrium is reported as converging in year 1.

Member previewVariant 3 · 3 implementations · 7 checks per implementation

Case contract

N[t+1] = r0*N/(1+(r0-1)*N/K); equilibrium K if r0>1 else 0; band = 0.01*K; hit = first year (0 = start) with |N-eq|<=band, else None; return [trajectory rounded 4, equilibrium, hit]; None for invalid inputs.

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: start at capacity	`[[1000.0, 1000.0, 1000.0, 1000.0], 1000.0, 1]`	`[[1000.0, 1000.0, 1000.0, 1000.0], 1000.0, 0]`	Failed

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