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https://issues.apache.org/jira/browse/RNG-70?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16886407#comment-16886407
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Alex D Herbert commented on RNG-70:
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{quote}Xorshift1024*, xorshift1024+, xorshift128+ and xoroshiro128+ fail
statistical tests for linearity
{quote}
Interesting. The [PCG website|http://www.pcg-random.org/blog/] written by the
same author has some blog discussion on this topic.
Recently we switched to using XorShift1024* for the SeedFactory. This improves
upon the Well44497b generator for quality of output but it should be noted that
it is a candidate for replacement if a 'better' RNG is added to the library.
> xoshiro generators
> ------------------
>
> Key: RNG-70
> URL: https://issues.apache.org/jira/browse/RNG-70
> Project: Commons RNG
> Issue Type: New Feature
> Components: core, simple
> Reporter: Alex D Herbert
> Assignee: Alex D Herbert
> Priority: Major
> Fix For: 1.3
>
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> The authors of the algorithm implemented in
> {{org.apache.commons.rng.core.source64.XorShift1024Star}} have produced new
> generators as described here:
> [xorshiro / xoroshiro generators|http://xoshiro.di.unimi.it]
> I propose to implement the *all purpose* algorithms using the following
> classnames:
> {code:java}
> source32.XoShiRo128StarStar
> source64.XoRoShiRo128StarStar
> source64.XoShiRo256StarStar
> source64.XoShiRo512StarStar
> source64.XorShift1024Phi
> {code}
> The algorithms are simple to adapt from the c source code and I have created
> working versions with units tests (analogous to the {{XorShift1024Star}}
> test).
> Each generator must have a corresponding name in the {{RandomSource}} enum. I
> propose:
> {code:java}
> XO_SHI_RO_128_SS,
> XO_RO_SHI_RO_128_SS,
> XO_SHI_RO_256_SS,
> XO_SHI_RO_512_SS,
> XOR_SHIFT_1024_PHI,
> {code}
> Note: XorShift1024Phi is an updated implementation of XorShift1024Star using
> a different multiplier. To share code this could be implemented by moving the
> implementation to an abstract base class for both XorShift1024Phi and
> XorShift1024Star which accepts the multiplier in the constructor.
> The authors also provide code for *faster generators* for use in creating
> floating-point random numbers where the lower order bits are discarded. These
> could be named:
> {code:java}
> source32.XoShiRo128Plus
> source64.XoRoShiRo128Plus
> source64.XoShiRo256Plus
> source64.XoShiRo512Plus
> XO_SHI_RO_128_PLUS,
> XO_RO_SHI_RO_128_PLUS,
> XO_SHI_RO_256_PLUS,
> XO_SHI_RO_512_PLUS,
> {code}
> For discussion:
> * The names of the generators.
> * Should the small state 64-bit generator XoRoShiRo128StarStar be
> implemented? It has a potentially confusing name clash with the 32-bit
> generator XoShiRo128StarStar. Speed is expected to be the same as
> XoShiRo256Star but using only half the memory footprint.
> * Should the faster floating-point generators be implemented?
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