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https://issues.apache.org/jira/browse/MATH-654?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Phil Steitz updated MATH-654:
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Affects Version/s: 1.1
1.2
2.0
2.1
Fix Version/s: 3.0
Thanks for reporting this. I assume you are using DIGEST_MODE. If this is the
case and you are comfortable compiling the code in trunk, the fix for MATH-634
enables a workaround for this. Using the reseed method added to
EmpiricalDistributionImpl in trunk, you can use ValueServer's
getEmpiricalDistribution to get the distribution and then invoke reseed.
Unfortunately, this method does not exist in any released version yet.
The problem is that ValueServer#getNextDigest (what it does for getNext in
DIGEST_MODE) delegates to EmpiricalDistributionImpl#getNextValue.
EmpiricalDistributionImpl has its own RandomData instance. To fix this issue,
EmpiricalDistirbutionImpl should add a constructor taking a RandomData and
ValueServer should provide this.
> ValueServer not deterministic for a fixed random number seed
> ------------------------------------------------------------
>
> Key: MATH-654
> URL: https://issues.apache.org/jira/browse/MATH-654
> Project: Commons Math
> Issue Type: Bug
> Affects Versions: 1.1, 1.2, 2.0, 2.1, 2.2
> Reporter: David James
> Assignee: Phil Steitz
> Fix For: 3.0
>
>
> I have built an agent-based model using the Apache Commons Math library,
> which has come in handy.
> The ValueServer seemed particularly helpful, as explained at:
> http://commons.apache.org/math/userguide/random.html
> My simulation needs repeatable randomness, so I used this form of the
> ValueServer constructor:
> ValueServer(RandomData randomData)
> Construct a ValueServer instance using a RandomData as its source of
> random data.
> //
> http://commons.apache.org/math/api-2.2/org/apache/commons/math/random/ValueServer.html
> However, in my simulation, I found that the ValueServer did not act
> deterministically if I supplied the same random number seed.
> I have not inspected the source code, but I suspect that the ValueServer is
> not using the `randomData` generator correctly. If it was, then it should be
> deterministic.
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