Monthly Math development meeting: 06/25/2020, 10 am EDT

Hey all,

The next monthly math meeting is on Thursday, June 25, 2020, 10 am Eastern time. (We postponed it one week.)

We have our monthly Math meetings on the third Thursday of the month. The next Math meeting is Thursday, June 18, 2020, 10 am Eastern time.

This will last no more than one hour; if we need more time, we will schedule additional time. (Sorry about the late notice… I thought I had already posted this message, but didn’t realize I didn’t.)

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.

Unfortunately, I won’t be able to be there tomorrow… I’ll try to find an alternative video chat solution that doesn’t require the host to be there (or at least allows for multiple hosts).

If any of you will be there for sure tomorrow, can you send over a Google Meet link and I’ll update the post?

We may move to next week?

Who will join tomorrow? I won’t be able to, but next week could work for me.

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I’m fine with moving it to next week

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Alright… postponed until next week. Thanks all. (I’m updating the post title, text, and the calendar invite.)

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Bumping this if anyone wants to join us in an hour.


Me and @rok_cesnovar are on. Join us if you want… I’ll take notes here in real-time like the last few meetings.

Right now, it’s @rok_cesnovar, @wds15, and me online.

@bbbales2 has joined us too.

@stevebronder joined.

@bbbales2: thanks to @wds15 for comments on ODE. @wds15: really cool that we can use variadic arguments for ODEs.

@stevebronder: close to first PR that adds the template on var. Added compiler flags to gcc. @bbbales2: will it happen before the templated matrix stuff? @stevebronder: leave it as a separate branch. All: we’re discussing merge conflicts for this. @wds15: asks when this would be ready. @stevebronder: wait until after the next release. @bbbales2: 2 downstream things: sparse matrices and static matrices.

@wds15: low-hanging fruit: @Daniel_Simpson’s PR. It’s almost ready. Does someone want to take over? @bbbales2: avoided it because it sounds like a lot of effort. To make it low hanging fruit, we need benchmarking at this level. @rok_cesnovar will try the benchmark. @bbbales2: thinks it’ll take half a day or a day of effort.

@wds15: ODEs. Move sensitivity to error checks. Is there a way to check it out? @bbbales2: don’t have enough time to shove it to the future. Use current option and go with that for now. @bbbales2: is the time step dependent on the tolerances of the sensitivities?

@wds15: asking @rok_cesnovar about changing init threadpool for CmdStan. init threadpool method was deprecated in the next version. @rok_cesnovar: do we want Stan Math to have a convenience function to init? Will look into an easier way of doing this.

@wds15: looking at ODE stuff, looking at error checking function. There’s a global function. Concern: globals bad for threading. @syclik: I will take action and document this (stan::error_index::value).

@stevebronder: Next release? @rok_cesnovar: 18 July, but that’s Saturday, so 20 July. 13 July (+/- day or two) will be code freeze.

@rok_cesnovar: asking about 3 releases a year instead of 4. All: just discussing the different things getting into this release.

We’re discussing the unnormalized distributions: Request for final feedback: User controlled unnormalized (propto) distribution syntax

@rok_cesnovar: new Windows RTools pass and old RTools pass. It seg faults due to large size.

@wds15: there’s more MPI code coming. How do we manage it? Looks like @yizhang wants to lead. Is ok taking position of removing MPI. @rok_cesnovar: the first problem is that not enough people know about MPI.