Avoid panic with almost-zero parameters for FisherF#39
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dhardy merged 1 commit intorust-random:masterfrom Dec 2, 2025
Merged
Avoid panic with almost-zero parameters for FisherF#39dhardy merged 1 commit intorust-random:masterfrom
dhardy merged 1 commit intorust-random:masterfrom
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These are too small to construct a ChiSquared distribution from.
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CHANGELOG.mdentrySummary
When
mornis a positive floating point value with0.5 m = 0.0(e.g. 1e-45 for f32, or 5e-324 for f64) the constructor of FisherF could panic in one of the unwrap() calls.Motivation
This is one of the unusual-parameter panics that I found by fuzzing, and fixing it turned out to be simple. (There's only a few more simple panics from fuzzing, and I expect fixing them before tackling the much trickier Binomial and Hypergeometric samplers may make things easier. And I'm not in a hurry :-). )
Details
The workaround is to reject FisherF distributions with
mornalmost zero instead of unwrapping. I expect that in practice people only use integralmandn.