FA-15917 / Floating-point arithmetic / Member archive
ULP lookup reports NaN as infinity · case 02
ULP lookup reports NaN as infinity.
Case contract
Return a finite binary64 ulp as a hex string; NaN maps to nan and either infinity maps to infinity. For subnormals and zero the ulp is the minimum positive subnormal.
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 |
|---|---|---|---|
| nan | "infinity" | "nan" | Failed |
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