FA-65372 / Ecological population dynamics / Member archive

Ricker map trajectory and dynamic regime: exponent grouping · case 02

Populations above carrying capacity turn negative instead of being pulled down smoothly.

Member previewVariant 2 · 3 implementations · 7 checks per implementation

Case contract

Regime by r: r<0 decline, r==0 neutral, 0<r<=1 monotone, 1<r<2 damped, 2<=r<2.526 cycle2, else complex; trajectory N[t+1]=N*exp(r*(1-N/K)) rounded 4; None for K<=0 or N0<0.

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: period doubling onset exactly 2	`["cycle2", [177.3373, -1013.3942, -83371.2616, -514212127.2252, -1.953771085285938e+16]]`	`["cycle2", [132.8047, 68.9089, 128.3303, 72.8208, 125.4096]]`	Failed

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