Alex D Herbert created RNG-93:
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Summary: SmallMeanPoissonSampler
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
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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