FA-17243 / Floating-point arithmetic / Member archive

Reciprocal retains the input exponent sign · case 03

Reciprocal retains the input exponent sign.

Member previewVariant 3 · 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
positive ordinary	`"5.3333333333"`	`"0.33333333333"`	Failed

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