FA-63768 / Actuarial life tables / Member archive
Pure endowment and survivorship accumulation: Accumulation uses survival from issue · case 03
The fund per survivor omits the benefit of survivorship.
Case contract
Input l (from issue age), n (0<=n<len(l) else 'invalid term'), i, g (premium escalation per mille), P. l_n=0 -> 'no survivors'. nEx = (l_n/l_0) v^n. Fund per survivor at n = sum_{k<n} P(1+g)^k (1+i)^(n-k) l_k/l_n (premiums at the start of each year). Return [nEx rounded 8, fund rounded half-up].
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 fixtureThis sample comes from the broken implementation of a controlled reproducer.
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| five-year accumulation | [0.76777729, 2850327] | [0.76777729, 2908794] | Failed |
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