FA-17257 / Floating-point arithmetic / Member archive

Reciprocal drops sign after magnitude normalization · case 02

Reciprocal drops sign after magnitude normalization.

Member previewVariant 2 · 3 implementations · 9 checks per implementation

Case contract

Compute the reciprocal of finite binary64 x using exponent decomposition. Signed zeros return signed infinity; overflow returns signed infinity and representable subnormal reciprocals are retained. 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 fixture

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

Boundary fixture	Actual	Expected	Outcome
negative ordinary	`"0.5"`	`"-0.5"`	Failed

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