Monthly Math development meeting: 05/21/2020

Hey all,

We have our monthly Math meetings on the third Thursday of the month. The next Math meeting is Thursday, May 21, 2020, 10 am Eastern time. This will last no more than one hour; if we need more time, we will schedule additional time.

This meeting is open to all those that currently contribute to the Math library or that would like to contribute to the Math library. If you’d like an invite to the Google Calendar event, please DM me with your Google handle. If you’d like to just have a copy of the event on your calendar, please use this link:

Direct Google Meet link:


  • this is a chance to collaborate and coordinate efforts. We’re expecting everyone to be kind and courteous. And patient. We have a team with diverse backgrounds.
  • impactful decisions will not be made at these meetings. That will continue to be done online on these forums. The meetings are a good time to discuss and get on the same page, but the decision making will be done online where we can include the opinions of others that can’t make the meeting.
  • important discussions that happen at the meeting will be communicated back online on these forums. If they don’t make it back here, it wasn’t important. No one will be penalized for not being present at a meeting.

If there’s anything you know you want to talk about, please post here. This is a good time to request help from others if there’s expertise that you need.

If anyone has specific agenda, please post them here. I’ll see you online tomorrow!

I am hoping I make it.

If I make it, we could discuss moving Windows Rtools 3.5 testing to Github Actions and moving Jenkins Windows agents to Rtools 4.0 : Using GitHub Actions on the Stan Math library


  • This would speedup Jenkins testing (we are currently limiting the parallel execution on Jenkins agents as the g++ 4.9.3 uses much more RAM and tests crash if too many parallel compilations are running).
  • faster testing would enable us to add more testing coverage for Windows (OpenCL, threading tests, etc) and stay in “finite” testing time
  • would enable “Jumbo” test files on windows which again speeds up testing
  • obviously adds testing coverage for Windows with RTools 4.0 to which I suspect our users will move soon. And we should be suggesting that also now that compiling with Rtools 4.0 will be ~2x faster:
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I’ll be posting live notes like last time… I think it was a lot easier to manage. I’m online now and if no one else shows up, no worries… I’ll just work on some parts of the Math library for the hour. Anyone is more than welcome to join and hang out.

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@bbbales2, @rok_cesnovar, and I are online.

We’re talking about the GitHub Actions and testing with RTools 4.0 on Windows.

Discussing where we should help next…


  • ODE stuff
  • variadic arguments
  • closures / functors
  • templated vars


  • @tadej is working on functions accepting Eigen expression
  • profiling
  • opencl
  • testing faster
    • larger files
    • distribution tests


  • will help distribution tests

Discussing MPI backend.

Meeting adjourned. That was fun. See you all next month!