FA-63440 / Actuarial life tables / Member archive

Select and ultimate mortality lookup: Survival subtracts rates instead of multiplying · case 05

Multi-year survival is slightly too low.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Input select {issue age: [q for durations 0..period-1]}, ultimate {attained age: q}, issue_age, period, dur, n. For each duration k in dur..dur+n-1 use the select rate row[issue][k] while k<period, else the ultimate rate at attained age issue+k. Missing rows -> 'no select row' / 'no ultimate rate'. Return [rates, survival over the n years rounded to 6].

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
new issue through select period	`[[70, 86, 104, 201, 213], 0.99326]`	`[[70, 86, 104, 201, 213], 0.993277]`	Failed

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