FA-16544 / Floating-point arithmetic / Member archive

NaN addition lets a quiet left operand hide a signaling right operand · case 04

NaN addition lets a quiet left operand hide a signaling right operand.

Member previewVariant 4 · 3 implementations · 14 checks per implementation

Case contract

Stipulated binary64 addition policy: propagate first signaling NaN, otherwise largest quiet-NaN diagnostic payload (left wins ties); quiet propagated NaNs preserving sign. Opposite infinities produce canonical quiet NaN. Finite values use Python binary64 addition. Return bits and invalid flag.

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
signaling precedence	`[9221120237041090660, true]`	`[9221120237041090564, true]`	Failed

MEMBER ARCHIVE

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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