[jira] [Created] (STATISTICS-84) Create the Mean from array input using a summation

["Alex Herbert (Jira)" <ji...@apache.org>]

Alex Herbert created STATISTICS-84:
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             Summary: Create the Mean from array input using a summation
                 Key: STATISTICS-84
                 URL: https://issues.apache.org/jira/browse/STATISTICS-84
             Project: Commons Statistics
          Issue Type: Improvement
          Components: descriptive
            Reporter: Alex Herbert


The creation of the Mean from an array uses the rolling mean algorithm. This requires a divide for each input value. The algorithm is slow when compared to a simple sum of the values and a divide of the sum. The advantage is that the algorithm is overflow safe and computes the mean in a single pass (useful for streams).

In the majority of use cases a sum will not overflow. Change the array construction to attempt a sum to compute the mean, reverting to the rolling mean if this fails.



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