FA-15937 / Floating-point arithmetic / Member archive

ULP scaling underflows below the subnormal spacing · case 02

ULP scaling underflows below the subnormal spacing.

Member previewVariant 2 · 3 implementations · 9 checks per implementation

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 fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
subnormal	`"0x0.0p+0"`	`"0x0.0000000000001p-1022"`	Failed

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