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Always discard at least 1 entry in new RNGs #3168

Closed WardBrian closed 1 year ago

WardBrian commented 1 year ago

Submission Checklist

Summary

This makes it so at least 1 entry is discarded from new RNG instances, even when chain == 0

Intended Effect

Closes #3167

How to Verify

See https://godbolt.org/z/G953v67c4 and the model/code provided in #3167

Side Effects

RNG seeds from previous versions of Stan will have different behavior for chain_id 0 and in the transformed data block. Users who did not use _rng functions in transformed data or manually set their chain id to 0 will not observe different behavior.

Documentation

None

Copyright and Licensing

Please list the copyright holder for the work you are submitting (this will be you or your assignee, such as a university or company):

Simons Foundation

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