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https://issues.apache.org/jira/browse/MATH-1068?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Gal Lalouche reopened MATH-1068:
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I've noticed a few more overflow issues for very large arrays (100k's), e.g.,
correlation < -1 or > 1.
Changing all the tiedX/Y/XYPairs, consecutiveX/Y/XYTies and swaps to long fixed
this.
> KendallsCorrelation suffers from integer overflow for large arrays.
> -------------------------------------------------------------------
>
> Key: MATH-1068
> URL: https://issues.apache.org/jira/browse/MATH-1068
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 3.3
> Reporter: Gal Lalouche
> Priority: Minor
> Labels: newbie
> Fix For: 3.3
>
> Original Estimate: 1m
> Remaining Estimate: 1m
>
> For large array size (say, over 5,000), numPairs > 10 million.
> in line 258, (numPairs - tiedXPairs) * (numPairs - tiedYPairs) possibly > 100
> billion, which will cause an integer overflow, resulting in a negative
> number, which will result in the end result in a NaN since the square-root of
> that number is calculated.
> This can easily be solved by changing line 163 to
> final long numPairs = ((long)n) * (n - 1) / 2; // to avoid overflow
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