[jira] [Updated] (RNG-81) NumberFactory to evenly sample all representable rationals between 0 and 1

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

     [ https://issues.apache.org/jira/browse/RNG-81?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Alex D Herbert updated RNG-81:
------------------------------
    Summary: NumberFactory to evenly sample all representable rationals between 0 and 1  (was: NumberFactory)

> NumberFactory to evenly sample all representable rationals between 0 and 1
> --------------------------------------------------------------------------
>
>                 Key: RNG-81
>                 URL: https://issues.apache.org/jira/browse/RNG-81
>             Project: Commons RNG
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.3
>            Reporter: Alex D Herbert
>            Assignee: Alex D Herbert
>            Priority: Major
>             Fix For: 1.3
>
>
> Change the number factory methods for {{nextFloat}} and {{nextDouble}}. 
> Currently the methods use:
>  * 23-bits of state from an int to create a float
>  * 52-bits of state from a long to create a double
> This method produces output floating point numbers with the final bit of the mantissa set to 0. The methods can be changed to use 24-bits and 53-bits of state respectively.
> This will match the implementation in {{java.util.SplittableRandom}}.
> Benchmarking has shown no noticeable difference in speed.
> Note that this change modifies the output {{float}} to evenly sample all {{k/2^-24}} [dyadic rationals|https://en.wikipedia.org/wiki/Dyadic_rational] and the {{double}} to evenly sample all {{k/2^-53}} dyadic rationals, i.e. the maximum number representable between 0 (inclusive) and 1.0 (exclusive).
>  



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