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Posted to dev@commons.apache.org by bu...@apache.org on 2003/11/14 05:22:37 UTC

DO NOT REPLY [Bug 24699] New: - repetitive permitations

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http://nagoya.apache.org/bugzilla/show_bug.cgi?id=24699

repetitive permitations

           Summary: repetitive permitations
           Product: Commons
           Version: Nightly Builds
          Platform: PC
        OS/Version: Windows NT/2K
            Status: NEW
          Severity: Normal
          Priority: Other
         Component: Math
        AssignedTo: commons-dev@jakarta.apache.org
        ReportedBy: skarupo@mail.ru


According to the API doc, the random permutations generated by RandomData.nextPermutation(int, int) are also supposed to be non-repetitive:

http://jakarta.apache.org/commons/sandbox/math/apidocs/org/apache/commons/math/random/RandomData.html#nextPermutation(int,%20int)

In fact, the inplementing class RandomDataImpl may produce identical permutations before all possible ones have been exhausted.

I just noticed this and loaded the lates build (Jar packed on Nov 1 2003) and the problem is still there...

For example, two successive calls to nextPermutation(2,2) may produce
{1, 0}
{1, 0}

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