v2.39.0 (19 May 2026)

• Added timing information to the output of standalone generated quantities. (#3373, #3377)
• Added a converged__ column to the output of the optimization algorithms,
  which documents why the optimization algorithm halted. A string explanation
  is also added as a comment. (#3379)
• Changes for compatibility with Eigen 5.0.1. (#3371)
• Fixed an issue where memory was being re-allocated unnecessarily. (#3392)

Documentation

HTML

• Stan User's Guide 2.39
• Stan Language Reference Manual 2.39
• Stan Language Functions Reference 2.39

PDF

• Stan User's Guide 2.39 pdf
• Stan Language Reference Manual 2.39 pdf
• Stan Language Functions Reference 2.39 pdf