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https://issues.apache.org/jira/browse/RNG-93?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alex D Herbert resolved RNG-93.
-------------------------------
Resolution: Fixed
Fix Version/s: 1.3
In master.
> SmallMeanPoissonSampler should require p0 to be positive
> --------------------------------------------------------
>
> Key: RNG-93
> URL: https://issues.apache.org/jira/browse/RNG-93
> Project: Commons RNG
> Issue Type: Bug
> Components: sampling
> Affects Versions: 1.3
> Reporter: Alex D Herbert
> Assignee: Alex D Herbert
> Priority: Trivial
> Fix For: 1.3
>
>
> The SmallMeanPoissonSampler accepts a mean up to 0.5 * Integer.MAX_VALUE.
> However at a value above approximately mean=744.44 the probability p0 is zero:
> {code:java}
> p0 = Math.exp(-mean);
> {code}
> This causes an impossible to reach condition within the sample loop and the
> sampler will always return a sample of the upper limit. This is:
> {code:java}
> limit = (int) Math.ceil(Math.min(1000 * mean, Integer.MAX_VALUE));
> {code}
> If the sampler is updated to reject any mean where p0 = 0 then this will
> serve as a warning to users that the sampler is invalid and they should
> switch to the LargeMeanPoissonSampler.
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