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From "Karl D. Gierach (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (MATH-1373) In LogNormalDistribution.java, it appears shape & scale are reversed/mis-labelled.
Date Sat, 18 Jun 2016 00:03:05 GMT

     [ https://issues.apache.org/jira/browse/MATH-1373?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Karl D. Gierach updated MATH-1373:
----------------------------------
    Attachment: MATH-1373.patch

this patch includes a revision to unit test which calcuates all expected shape and scale parameters
based on the mean and variance of the unscaled data.

> In LogNormalDistribution.java, it appears shape & scale are reversed/mis-labelled.
> ----------------------------------------------------------------------------------
>
>                 Key: MATH-1373
>                 URL: https://issues.apache.org/jira/browse/MATH-1373
>             Project: Commons Math
>          Issue Type: Bug
>    Affects Versions: 3.6.1
>            Reporter: Karl D. Gierach
>            Priority: Minor
>         Attachments: MATH-1373.patch
>
>   Original Estimate: 1h
>  Remaining Estimate: 1h
>
> When I compute the logshape and log scale based on the formulas on wikipedia's lognormal
distribution page that use empirical mean and variance, I found that the getNumericalMean()
method was not returning the empirical mean.
> However, upon just trying to reverse the shape and scale parameters in the constructor
proved to fix the problem, and the object then returns the correct empirical mean.



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