FA-63740 / Actuarial life tables / Member archive

Double-decrement death and lapse table: Decrement lists of different length are truncated · case 05

Missing lapse rates silently shorten the projection.

Member previewVariant 5 · 3 implementations · 9 checks per implementation

Case contract

Input qd, qw (associated single-decrement rates per 100000, equal lengths else 'length mismatch'), timing udd|eoy, radix. UDD in each decrement: q(d)=q'd(1-q'w/2), q(w)=q'w(1-q'd/2). eoy (lapses at year end): q(d)=q'd, q(w)=(1-q'd)q'w. Each year counts are rounded half-up and subtracted from l. Return [[deaths, lapses] per year, final l].

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
length mismatch	`[[[10, 50], [18, 56]], 866]`	`"length mismatch"`	Failed

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