# StanCon Cambridge developer meeting opportunities

**URL:** <https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743>\
**Category:** Developers\
**Created:** [July 16, 2019, 2:15pm UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743 "2019-07-16T14:15:44Z")\
**Posts on this page:** 20\
**Page:** 1

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**Author:** ![avehtari](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/avehtari/32/5935_2.png) [@avehtari](https://discourse.mc-stan.org/u/avehtari)\
**Post date:** [July 16, 2019, 2:15pm UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/1 "2019-07-16T14:15:44Z")

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During StanCon there will be time for planned and ad-hoc Stan developer meetings on Tuesday and Wednesday. This will be managed by having a longer lunch break between the tutorials and some reserved rooms. Idea is that you have possibility to have some face-to-face discussion with people you don’t often meet live and maybe even do some code review and pair programming (which are definitely easier when in the same room). Based on the previous StanCons it can be quite busy during the actual conference, so if you haven’t finalized your travel plans, I suggest to arrive so that you can take benefit of the opportunity of live meetings on Tuesday and Wednesday. Most of the meetings are assumed to be quite small scale with anyone you want to meet (just contact them in your preferred way), but anyone is welcome to suggest also more planned meetings (e.g. by posting to this thread).

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**Author:** ![breckbaldwin](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/breckbaldwin/32/9052_2.png) [@breckbaldwin](https://discourse.mc-stan.org/u/breckbaldwin)\
**Post date:** [July 16, 2019, 4:21pm UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/2 "2019-07-16T16:21:35Z")

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As a StanCon organizer I’ll chime in.

My goal is to have 2 hrs/day for developer meetings during tutorials. This will NOT overlap the tutorials.

During the conference I am aiming for at least 1 hr/day of developer meeting time but I am more constrained and cannot promise it.

If you want access to the tutorial food/lunch please register for tutorials. That is how we pay for the food.

thanks

Breckl

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**Author:** ![avehtari](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/avehtari/32/5935_2.png) [@avehtari](https://discourse.mc-stan.org/u/avehtari)\
**Post date:** [August 1, 2019, 8:02am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/3 "2019-08-01T08:02:10Z")

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Some topics I’d like to discuss live and anyone interested in these is welcome to join

- bayesplot for visual convergence and model diagnostics (at least with @jonah, @paul.buerkner)
- loo (at least with @jonah, @paul.buerkner, @mans_magnusson)
- projpred (at least with @jonah, @paul.buerkner, @bgoodri)
- Laplace for GLVMs (at least with @charlesm93, @stevebronder, @bgoodri, @mitzimorris)
- sparse matrices (at least with @stevebronder, @bgoodri, @seantalts)

EDIT: accidentally posted too early

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**Author:** ![syclik](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/syclik/32/6_2.png) [@syclik](https://discourse.mc-stan.org/u/syclik)\
**Post date:** [August 1, 2019, 8:12am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/4 "2019-08-01T08:12:24Z")

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> [@avehtari](#):
>
> sparse matrices (at least with @Stevo15025, @bgoodri, @seantalts)

Count me in.

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**Author:** ![stevebronder](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/stevebronder/32/17242_2.png) [@stevebronder](https://discourse.mc-stan.org/u/stevebronder)\
**Post date:** [August 1, 2019, 8:29am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/5 "2019-08-01T08:29:32Z")

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Do we want to have these developer meetings on the same day or should we split them up across the conference?

I also wouldn’t mind having one for stan-math performance. i.e. cpu/gpu parallelism and Eigen/math optimizations

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**Author:** ![wds15](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/wds15/32/908_2.png) [@wds15](https://discourse.mc-stan.org/u/wds15)\
**Post date:** [August 1, 2019, 9:19am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/6 "2019-08-01T09:19:40Z")

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A meeting on the cpu parallel things with a discussion on changes to the reverse ad system would be good, I think.

I am around from Wednesday just before lunch.

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**Author:** ![anon75146577](https://avatars.discourse-cdn.com/v4/letter/a/f07891/32.png) [@anon75146577](https://discourse.mc-stan.org/u/anon75146577)\
**Post date:** [August 1, 2019, 1:24pm UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/7 "2019-08-01T13:24:49Z")

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I’ll be available to video in. Just keep me up to date

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**Author:** ![seantalts](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/seantalts/32/32_2.png) [@seantalts](https://discourse.mc-stan.org/u/seantalts)\
**Post date:** [August 1, 2019, 1:40pm UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/8 "2019-08-01T13:40:56Z")

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Sparse matrices sound fun! @stevebronder was talking about writing up a design doc for how the syntax would look and how it would work. I think there’s some existing work from @anon75146577 [here](https://discourse.mc-stan.org/t/a-proposal-for-sparse-matrices-and-gps-in-stan/2183) (which possibly supercedes [the wiki](https://github.com/stan-dev/stan/wiki/Functional-Spec:-Sparse-Matrix-Data-Types)). Are those the most up to date links?

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**Author:** ![charlesm93](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/charlesm93/32/4634_2.png) [@charlesm93](https://discourse.mc-stan.org/u/charlesm93)\
**Post date:** [August 2, 2019, 5:50am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/9 "2019-08-02T05:50:58Z")

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I’d like to discuss the KINSOL solver with @yizhang and @wds15. Specifically, what features do we make available to the user – KINSOL offers a lot, and sometimes you need fine-tuning to get the optimal performance. I’ll draft a proposal.

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**Author:** ![stevebronder](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/stevebronder/32/17242_2.png) [@stevebronder](https://discourse.mc-stan.org/u/stevebronder)\
**Post date:** [August 2, 2019, 7:01am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/10 "2019-08-02T07:01:38Z")

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Yes! Going to start working on the proposal today. I’m lucky that Dan and Aki have already paved the way for a lot of these things

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**Author:** ![yizhang](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/yizhang/32/15673_2.png) [@yizhang](https://discourse.mc-stan.org/u/yizhang)\
**Post date:** [August 2, 2019, 3:14pm UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/11 "2019-08-02T15:14:56Z")

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> [@wds15](#):
>
> A meeting on the cpu parallel things with a discussion on changes to the reverse ad system would be good, I think.

> [@charlesm93](#):
>
> I’d like to discuss the KINSOL solver with @yizhang and @wds15. Specifically, what features do we make available to the user – KINSOL offers a lot, and sometimes you need fine-tuning to get the optimal performance. I’ll draft a proposal.

These two topics overlap and I’d suggest we also join the sparse matrices discussion @avehtari mentioned.

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**Author:** ![yizhang](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/yizhang/32/15673_2.png) [@yizhang](https://discourse.mc-stan.org/u/yizhang)\
**Post date:** [August 2, 2019, 3:37pm UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/12 "2019-08-02T15:37:45Z")

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To echo what @jonah mentioned two weeks ago, I wonder what activities can be arranged for people who won’t be in dev meeting, 2 hours is a long gap in the middle of the day.

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**Author:** ![avehtari](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/avehtari/32/5935_2.png) [@avehtari](https://discourse.mc-stan.org/u/avehtari)\
**Post date:** [August 3, 2019, 10:32am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/13 "2019-08-03T10:32:50Z")

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In Helsinki, many people attending the tutorials wished for longer breaks without any organized activities so that they can either experiment with what they learned in the morning or rest so that they are able to learn more in the afternoon. Thus this 2 hour break is intentional and it’s just the developers who have to suffer and manage without a longer break.

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**Author:** ![mans\_magnusson](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/mans_magnusson/32/7093_2.png) [@mans\_magnusson](https://discourse.mc-stan.org/u/mans_magnusson)\
**Post date:** [August 5, 2019, 7:36am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/14 "2019-08-05T07:36:13Z")

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Yay! Im in!

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**Author:** ![stevebronder](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/stevebronder/32/17242_2.png) [@stevebronder](https://discourse.mc-stan.org/u/stevebronder)\
**Post date:** [August 5, 2019, 8:58am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/15 "2019-08-05T08:58:12Z")

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I offered to help Aki with arranging these. Below are polls for each developer block mentioned. If you are interested in attending any of the developer meetings leave the dates you are available so we can get space accordingly!

If you can attend any day feel free to check-off all 4 days

@breckbaldwin once we have the dates that are best for everyone who do we contact to either see which rooms are free or reserve rooms?

Also, I kind of like the idea of making these meetings open. It could be a good opportunity to get new developers!

Thinking about this more, how would people feel about a “new devs” block? I kind of like the idea of collecting a bunch of small PRs across our packages and helping setup people who are interested in contributing.

# Bayesplot

_Poll ([view on site](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/15))_

# loo

_Poll ([view on site](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/15))_

# projpred

_Poll ([view on site](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/15))_

# Laplace for GLVMs (and Kinsol Solver)

_Poll ([view on site](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/15))_

# Sparse Matrices

_Poll ([view on site](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/15))_

# Parallelization / Optimization

_Poll ([view on site](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/15))_

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<div class="post-metadata">

**Author:** ![avehtari](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/avehtari/32/5935_2.png) [@avehtari](https://discourse.mc-stan.org/u/avehtari)\
**Post date:** [August 5, 2019, 9:01am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/16 "2019-08-05T09:01:30Z")

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> [@stevebronder](#):
>
> Thinking about this more, how would people feel about a “new devs” block? I kind of like the idea of collecting a bunch of small PRs across our packages and helping setup people who are interested in contributing.

tidyverse had dev day with Hadley ringing a gong every time a PR was merged

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**Author:** ![stevebronder](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/stevebronder/32/17242_2.png) [@stevebronder](https://discourse.mc-stan.org/u/stevebronder)\
**Post date:** [August 5, 2019, 9:02am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/17 "2019-08-05T09:02:48Z")

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Yes my idea is v much inspired by that! They had a new dev event at a Chicago SatRday that went very well!

Surely Cambridge has a gong around somewhere we can borrow…

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**Author:** ![stevebronder](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/stevebronder/32/17242_2.png) [@stevebronder](https://discourse.mc-stan.org/u/stevebronder)\
**Post date:** [August 5, 2019, 9:16am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/18 "2019-08-05T09:16:32Z")

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> [@wds15](#):
>
> A meeting on the cpu parallel things with a discussion on changes to the reverse ad system would be good, I think.

One thing I’d like to discuss wrt this is our memory model. I made a [branch](https://github.com/stan-dev/math/tree/feature/concept-chainable-allocator) of stan-math which has a C++20 Allocator concept compliant allocator in it. (mostly ~~stolen~~ inspired by `Eigen` and Facebook’s `folly`). So instead of using raw pointers like `vari**` we can use something like

```no-highlight
std::vector<vari, chainable_allocator<vari>> adjARef_;

```

I think we can take this idea a step further by creating a pool of stack allocators, where we have a number of allocators equal to the number of threads available. I think we could do this by using the Bloomberg style of dynamic polymorphic allocator in the initializer. So something like

```cpp
std::vector<vari> adjARef_;
// In the initialization list
adjARef_(A.vi(), pooled_stack_allocators<vari>)

```

Then the `pooled_stack_allocator` gives a stack allocator for `vari` to `adjARef_`.

I think that makes sense? Though we should probably discuss this somewhere else

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**Author:** ![breckbaldwin](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/breckbaldwin/32/9052_2.png) [@breckbaldwin](https://discourse.mc-stan.org/u/breckbaldwin)\
**Post date:** [August 5, 2019, 2:11pm UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/19 "2019-08-05T14:11:00Z")

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> [@stevebronder](#):
>
> @breckbaldwin once we have the dates that are best for everyone who do we contact to either see which rooms are free or reserve rooms?

I believe there are plenty of rooms. I have scheduled 2hrs of dev time Tues/Wed, 1 hr on Friday. I was thinking of a general community meeting Thursday for an hour as well. Schedules up today/tomorrow.

Breck

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**Author:** ![mans\_magnusson](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/mans_magnusson/32/7093_2.png) [@mans\_magnusson](https://discourse.mc-stan.org/u/mans_magnusson)\
**Post date:** [August 16, 2019, 6:45am UTC](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743/20 "2019-08-16T06:45:52Z")

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We spoke yesterday about have a short discussion about the posterior database as well. I do not know where that would fit. @avehtari may have an idea?

[Next page](https://discourse.mc-stan.org/t/stancon-cambridge-developer-meeting-opportunities/9743.md?page=2)