RFR: 8326227: Rounding error that may distort computeNextGaussian results [v3]

[Chris Hennick]

On Wed, 12 Jun 2024 10:08:02 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

>>> Update: confirmed that the new test fails without the fix.
>> 
>> Thanks for verifying the test checks the fix; I'll let others who have worked more directly on the random code review the actual fix.
>
>> @jddarcy Added a regression test, and currently working on adjusting it (see https://github.com/Pr0methean/jdk/actions/runs/7984444127) to ensure we have a case that fails without the fix, passes with the fix, and is practical to run within the usual unit-test timeouts.
> 
> I gave this a try locally. It doesn't fail for me without the source code changes proposed in this PR. I see the following output from the test without the source code changes:
> 
> 
> got 1.0 for max 1.0
> got 2.0 for max 2.0
> got 3.0 for max 3.0
> got 4.0 for max 4.0
> got 5.0 for max 5.0
> got 6.0 for max 6.0
> got 7.0 for max 7.0
> got 11.353912041222094 for max 8.0
> got 11.353912041222094 for max 9.0
> 
> 
> With the proposed changes in this PR, the test continues to pass and I see this output:
> 
> 
> got 7.569274694148063 for max 1.0
> got 7.569274694148063 for max 2.0
> got 7.569274694148063 for max 3.0
> got 7.569274694148063 for max 4.0
> got 7.569274694148063 for max 5.0
> got 7.569274694148063 for max 6.0
> got 7.569274694148063 for max 7.0
> got 11.353912041222094 for max 8.0
> got 11.353912041222094 for max 9.0

@jaikiran Thanks for these results; I'll take another look at the test over the weekend.

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PR Comment: https://git.openjdk.org/jdk/pull/17703#issuecomment-2278574602