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https://issues.apache.org/jira/browse/MATH-186?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12565235#action_12565235
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Phil Steitz commented on MATH-186:
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For this to happen with other JVM impls with the change just made, the jvm
would have to produce different results for the exact same computations, which
would be odd. Equals is strictly defined for this class, which I think is OK
and the test is really supposed to just be testing equals and hashcode.
> test results depend on java version
> -----------------------------------
>
> Key: MATH-186
> URL: https://issues.apache.org/jira/browse/MATH-186
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 1.2
> Environment: GNU/Linux (ubuntu Gutsy Gibbon), java 1.3: eclipse
> compiler, java 1.4: Blackdown-1.4.2-02, java 1.6: SUN 1.6.0_03-b05, AMD
> athlon XP2000+
> Reporter: Luc Maisonobe
> Priority: Minor
> Fix For: 1.2
>
>
> Running the tests with maven and changing the java version used by changing
> JAVA_HOME in the ~/.mavenrc file, I get different results.
> With the Eclipse compiler set to 1.3 compatibility and with blackdown jvm
> (1.4), the tests succed.
> With the Sun jvm (1.6), SummaryStatisticsAbstractTest.testEqualsAndHashCode
> (which is used both by SummaryStatisticsTest and
> SynchronizedSummaryStatisticsTest) fails.
> The error is related to geometric mean computation, which lead to slightly
> different results depending on the order of added elements. One instance
> returns 2.213363839400643 and the other returns 2.2133638394006434. Both
> results are consistent with IEEE754 arithmetic (they differ in the last two
> bits).
> Using Sun 1.6.0_03 jvm, the different values induce a test failure when
> SummaryStatistics.equals() method is called (it checks for exact equality).
> If this part of the test is commented out, another failure occurs when the
> SummaryStatistics.hashcode() method is called.
> Changing the equals method would be possible, but would be a change of
> semantics and would imply choosing some threshold which would never suit
> everybody needs. Changing the hashcode method simply does not seem realistic
> to me. So I would like to keep these methods as they are now. So the main
> conclusion would be that the test is too sensitive to jvm implementation
> (which are consistent with IEEE754 arithmetic in this case).
> I don't know what to do about this issue.
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