FA-65385 / Ecological population dynamics / Member archive

Beverton-Holt recruitment convergence: density denominator · case 05

The stock settles well below the stated carrying capacity.

Member previewVariant 5 · 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: slow approach	`[[14.7059, 21.4286, 30.8219, 43.5484, 60.089, 80.4636, 103.9646, 129.1027, 153.9129, 176.5291, 195.7002, 210.9747], 500.0, null]`	`[[14.8515, 21.9512, 32.2196, 46.8208, 67.09, 94.3079, 129.2706, 171.709, 219.8186, 270.309, 319.1849, 362.9343], 500.0, null]`	Failed

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