[jira] [Created] (RNG-124) Create fixed increment PCG generators

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

Alex Herbert created RNG-124:
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             Summary: Create fixed increment PCG generators
                 Key: RNG-124
                 URL: https://issues.apache.org/jira/browse/RNG-124
             Project: Commons RNG
          Issue Type: Improvement
          Components: core, simple
    Affects Versions: 1.3
            Reporter: Alex Herbert
            Assignee: Alex Herbert


The increment of the PCG generator serves to select the underlying linear congruential generator (LCG) from 2 classes of related generators. Thus initialisation of generators using different increments can result in PCG output with massive correlations. The result is that seeding with 128-bits does not reduce the chance of correlated output over seeding with just 64-bits and using a fixed increment. See RNG-123.

Create a fixed increment version of the three PCG generators which currently accept the increment in their seed:
{noformat}
PCG_XSH_RR_32    => PCG_XSH_RR_32_OS
PCG_XSH_RS_32    => PCG_XSH_RS_32_OS
PCG_RXS_M_XS_64  => PCG_RXS_M_XS_64_OS
{noformat}
Here the {{_OS}} suffix represents One Sequence. The equivalent PCG generators in the reference c++ source code have a _oneseq suffix.



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