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Cohort rates from a period table: The last requested age is omitted · case 04

Cohort survival stops one age short.

Member previewVariant 4 · 3 implementations · 6 checks per implementation

Case contract

Input table {year: [q per 100000 by age from 0]}, cohort birth year, ages a0..a1. Cohort rate at age a is table[cohort+a][a]; years after the last tabulated year use the last year; years before the first -> 'missing year <y>'; missing ages -> 'missing age <a>'. Return [rates, survival over the ages rounded 8].

Why this case matters

Life-table arithmetic compounds across ages, so one misplaced index or assumption shifts every downstream value.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
cohort inside table	`[[510, 514, 518, 522, 526, 530], 0.96920279]`	`[[510, 514, 518, 522, 526, 530, 534], 0.96402724]`	Failed

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