FA-15463 / Numerics / Member archive
Exact ldl decomposition: lower factor diagonal divisor · case 03
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]], [[-1, 5], [1, 1], [0, 1]], [[-3, 10], [49, 75], [1, 1]]], [[20, 1], [71, 5], [200779, 28125]]] | [[[[1, 1], [0, 1], [0, 1]], [[-1, 5], [1, 1], [0, 1]], [[-3, 10], [49, 71], [1, 1]]], [[20, 1], [71, 5], [457, 71]]] | Failed |
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