# Fitting ODE models: best/efficient practices?

**URL:** <https://discourse.mc-stan.org/t/fitting-ode-models-best-efficient-practices/21018>\
**Category:** General\
**Tags:** ode\
**Created:** [February 26, 2021, 7:16pm UTC](https://discourse.mc-stan.org/t/fitting-ode-models-best-efficient-practices/21018 "2021-02-26T19:16:16Z")\
**Posts on this page:** 1\
**Showing post:** 47

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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:** [March 3, 2021, 9:43pm UTC](https://discourse.mc-stan.org/t/fitting-ode-models-best-efficient-practices/21018/47 "2021-03-03T21:43:27Z")

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> [@Funko\_Unko](#):
>
> How can I help? As in what is the best way to start?

That’s fantastic, thank you! There’s actually an ongoing discussion within [@SGB](https://discourse.mc-stan.org/groups/sgb) on how we can regularly update our roadmap like what [Rust has been doing](https://blog.rust-lang.org/2020/09/03/Planning-2021-Roadmap.html), to help planning and bringing in new contributors. While this effort is underway, things that come to my mind that might interest you include

- A friendly user guidance on how to select ODE solvers and control parameters, e.g. [here](https://github.com/stan-dev/docs/issues/283) and [here](https://github.com/stan-dev/docs/pull/333), @bbbales2 will love this.
- [Auto-selecting ODE integrators and stiffness/non-stiffness detection](https://discourse.mc-stan.org/t/switching-ode-integrators-between-the-warmup-and-the-sampling-phase/15859).
- [delay-differential equations](https://discourse.mc-stan.org/t/is-it-possible-to-solve-delay-differential-equation/3442).
- As to [cross-chain warmup](https://discourse.mc-stan.org/t/cross-chain-warmup-adaptation-using-mpi/12912) aka campfire, currently there’s an experimental MPI implementation in [Torsten](https://github.com/metrumresearchgroup/Torsten/tree/develop), a Stan fork for pharmacometrics applications. To bring it into Stan, there needs to be
  - more benchmark,
  - refactoring Stan’s MPI infrastructure (or a multithreading implementation based on @wds15 's work on TBB)
  - refactoring the HMC sampler

- or generally anything mentioned in this thread

I myself don’t know much of R either, and only slightly better in that regard on c++. Fortunately those things are frequently consulted on this forum and our community has been very helpful.

EDIT: forgot to mention that this [issue](https://github.com/stan-dev/math/issues/2395) could be a good entry to Stan Math underworld.

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