FA-16674 / Floating-point arithmetic / Member archive

Stochastic rounding truncates the probability before sampling · case 04

Stochastic rounding truncates the probability before sampling.

Member previewVariant 4 · 3 implementations · 10 checks per implementation

Case contract

Stipulated stochastic rounding of nonnegative significand with exact dyadic remainder rem/2**k. Draw is uniform integer in [0,2**k); increment magnitude iff draw<rem, then apply sign. Exact results never increment. Return rounded value and whether magnitude incremented.

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
draw below	`[4, false]`	`[5, true]`	Failed

MEMBER ARCHIVE

The complete case is available to members.

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

Member access is invitation-based. Sign in with your invited account to inspect the sources.