FA-65384 / Ecological population dynamics / Member archive

Beverton-Holt recruitment convergence: density denominator · case 04

The stock settles well below the stated carrying capacity.

Member previewVariant 4 · 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: herring recruitment	`[[142.8571, 375.0, 818.1818, 1350.0, 1723.4043, 1898.4375, 1964.9596, 1988.1818, 1996.045, 1998.6799], 1000.0, null]`	`[[136.3636, 321.4286, 586.9565, 810.0, 927.4809, 974.5989, 991.3871, 997.1125, 999.0356, 999.6783], 1000.0, 7]`	Failed

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