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https://issues.apache.org/jira/browse/STATISTICS-83?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alex Herbert resolved STATISTICS-83.
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Resolution: Won't Fix
Don't fix behaviour on (edge case) non-finite results on the basis of
performance.
> Mean returns a non-finite value that can be incorrect
> -----------------------------------------------------
>
> Key: STATISTICS-83
> URL: https://issues.apache.org/jira/browse/STATISTICS-83
> Project: Commons Statistics
> Issue Type: Bug
> Components: descriptive
> Reporter: Alex Herbert
> Priority: Trivial
>
> The Mean maintains a non-finite value to return in the event that the input
> contains non-finite values and the result is not finite.
> The non-finite value is a simple sum of the input. This returns the correct
> result for most cases of nan/infinte values. However if the values contain
> only one sign of infinity and the other finite values overflow to an opposite
> infinity before the infinity is encountered the result is incorrect (due to
> +inf + -inf == nan), e.g. the following test fails:
> {code:java}
> double[] values = {Double.MAX_VALUE, Double.MAX_VALUE,
> Double.NEGATIVE_INFINITY};
> // Computed value = NaN
> Assertions.assertEquals(Double.NEGATIVE_INFINITY,
> Mean.of(values).getAsDouble());
> {code}
> Investigate alternative options for non-finite results and either: correct
> the support; or drop support if performance is significantly impacted in
> order to handle for these rare cases.
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