FA-17019 / Floating-point arithmetic / Member archive
Log divided difference normalizes its increment by the destination · case 04
Log divided difference normalizes its increment by the destination.
Case contract
Evaluate (log(b)-log(a))/(b-a) for positive finite endpoints with continuous limit 1/a. Close ratios use log1p; fixtures have finite outputs. Finite results are rendered to eleven significant decimal digits; modeled domain violations and arithmetic errors are explicit strings.
Why this case matters
An offline floating representation model isolates a reproducible arithmetic fault.
One recorded failure
Sample boundary fixtureThis sample comes from the broken implementation of a controlled reproducer.
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| moderate close | "0.84288412526" | "0.94226428525" | Failed |
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