FA-16218 / Floating-point arithmetic / Member archive

Inverse tangent replaces positive pole with zero · case 03

Inverse tangent replaces positive pole with zero.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Evaluate inverse hyperbolic tangent on [-1,1], with signed infinite endpoints and a domain marker outside. 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 endpoint	`"0"`	`"+infinity"`	Failed

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