FA-16027 / Floating-point arithmetic / Member archive

Mantissa carry does not advance the exponent · case 02

Mantissa carry does not advance the exponent.

Member previewVariant 2 · 3 implementations · 14 checks per implementation

Case contract

Encode finite exactly represented dyadic x into sign/4-bit-exponent/3-bit-fraction toy float with bias 7, gradual underflow, round-to-nearest-even and infinity overflow. Return the unsigned byte. The miniature format is stipulated, not a hardware conformance claim.

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
binade carry	`56`	`64`	Failed

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