FA-16764 / Floating-point arithmetic / Member archive

Sine-pi fails to reflect the near-integer positive residual · case 04

Sine-pi fails to reflect the near-integer positive residual.

Member previewVariant 4 · 3 implementations · 11 checks per implementation

Case contract

Evaluate sin(pi*x) for finite x using modulo-two reduction, with exact integer zeros carrying the sign of x and exact half-integer extrema. 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
near integer	`"2.8573924409e-12"`	`"2.8572618736e-12"`	Failed

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