FA-63803 / Actuarial life tables / Member archive

Cohort rates from a period table: Years before the table are silently back-filled · case 03

Old cohorts are given rates from later years.

Member previewVariant 3 · 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 starts before first year	`[[536, 543, 550, 557, 564, 571, 575, 579], 0.95611631]`	`"missing year 1995"`	Failed

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