FA-15465 / Numerics / Member archive
Exact ldl decomposition: lower factor diagonal divisor · case 05
The exact exact ldl decomposition result violates the stated contract at lower factor diagonal divisor.
Case contract
Input symmetric positive definite integer matrix; return unit lower L and diagonal D as rational pairs such that A=L*D*Ltranspose.
Why this case matters
Exact discrete arithmetic with observable algorithmic state; no floating point approximation is used.
One recorded failure
Sample boundary fixtureThis sample comes from the broken implementation of a controlled reproducer.
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| explicit oracle 0 | [[[[1, 1], [0, 1], [0, 1]], [[-2, 3], [1, 1], [0, 1]], [[-1, 9], [1, 21], [1, 1]]], [[18, 1], [6, 1], [5629, 441]]] | [[[[1, 1], [0, 1], [0, 1]], [[-2, 3], [1, 1], [0, 1]], [[-1, 9], [1, 9], [1, 1]]], [[18, 1], [6, 1], [343, 27]]] | Failed |
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