[jira] [Resolved] (RNG-20) Initial state diversity

["Gilles (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/RNG-20?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Gilles resolved RNG-20.
-----------------------
    Resolution: Implemented

commit 819d8a5443988a0b864ea3bc5d79a461ca1fa3db

> Initial state diversity
> -----------------------
>
>                 Key: RNG-20
>                 URL: https://issues.apache.org/jira/browse/RNG-20
>             Project: Commons RNG
>          Issue Type: Improvement
>            Reporter: Gilles
>            Assignee: Gilles
>            Priority: Minor
>             Fix For: 1.0
>
>
> A generator usually _assumes_ that its initial state is "sufficiently diverse" for it to perform correctly.
> For example, it is known that some algorithms (e.g. "Mersenne Twister") will be "stuck" by the all-zero state.
> To ensure diversity when the seed (passed by the user) contains less information than the state can hold, {{SeedFactory}} provides a {{fillState}} method to be called from within the {{setSeedInternal}} method of an RNG implementation.
> In this ticket, it is proposed that the actual code (for replacing zeroes in the initial state) is inspired from the one that already existed in class {{AbstractWell}}.
> Note: neither the code in {{AbstractWell}} nor another code, in {{MersenneTwister}} and  {{MersenneTwister64}} (with a similar purpose), will be replaced by a call to {{fillState}} because for those algorithms, the filling procedure is part of the reference code (and is thus necessary in order to reproduce the exact same output).



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