# Latest

**URL:** https://discourse.pymc.io/latest.md?page=1

[Latest](https://discourse.pymc.io/latest.md) · [Categories](https://discourse.pymc.io/categories.md) · [Tags](https://discourse.pymc.io/tags.md)

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## [New contributor looking for guidance: from issue fixes to sustained PyMC contributions](https://discourse.pymc.io/t/new-contributor-looking-for-guidance-from-issue-fixes-to-sustained-pymc-contributions/17604)

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**Author:** [@Sanket1](https://discourse.pymc.io/u/Sanket1)\
**Replies:** 2\
**Last updated:** [September 12, 2026, 8:42am UTC](https://discourse.pymc.io/t/new-contributor-looking-for-guidance-from-issue-fixes-to-sustained-pymc-contributions/17604 "2026-09-12T08:42:22Z")

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Hi everyone, I’m a contributor working to move from isolated issue fixes to steady PyMC contributions. I’ve started with a docs improvement in the main repo (updating learn/usage\_overview and linking it in Learn naviga…

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## [🚀 Release pymc-extras v0.15.0](https://discourse.pymc.io/t/release-pymc-extras-v0-15-0/17932)

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**Author:** [@pymc-bot](https://discourse.pymc.io/u/pymc-bot)\
**Replies:** 0\
**Last updated:** [September 11, 2026, 12:52pm UTC](https://discourse.pymc.io/t/release-pymc-extras-v0-15-0/17932 "2026-09-11T12:52:43Z")

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A new release of pymc-extras is now available! :package: Release Information Version: v0.15.0 Repository: pymc-devs/pymc-extras Release Page: Release v0.15.0 · pymc-devs/pymc-extras · GitHub Note: It may take some time…

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## [What's the best way to fit a statespace model to multiple time series](https://discourse.pymc.io/t/whats-the-best-way-to-fit-a-statespace-model-to-multiple-time-series/17924)

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**Author:** [@JSR](https://discourse.pymc.io/u/JSR)\
**Replies:** 5\
**Last updated:** [September 11, 2026, 4:21am UTC](https://discourse.pymc.io/t/whats-the-best-way-to-fit-a-statespace-model-to-multiple-time-series/17924 "2026-09-11T04:21:57Z")

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Suppose I’m modeling a simple VAR type system, x\_{t+1} = Ax\_{t} + b\_t+\\varepsilon\_t, and I have collected multiple samples/timeseries, with varying initial conditions and potentially different b\_t terms (A is the same fo…

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## [DEMetropolis stalls with progressbar=True](https://discourse.pymc.io/t/demetropolis-stalls-with-progressbar-true/17925)

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**Author:** [@excaliburrrrrrrrr](https://discourse.pymc.io/u/excaliburrrrrrrrr)\
**Replies:** 6\
**Last updated:** [September 9, 2026, 9:07am UTC](https://discourse.pymc.io/t/demetropolis-stalls-with-progressbar-true/17925 "2026-09-09T09:07:49Z")

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Hi everyone, I rely on MCMC progress and estimated remaining time to schedule subsequent computations. With parallel DEMetropolis, enabling the progress bar appears to stall my job. Disabling it allows completion, but l…

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## [🚀 Release v6.3.2](https://discourse.pymc.io/t/release-v6-3-2/17927)

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**Author:** [@pymc-bot](https://discourse.pymc.io/u/pymc-bot)\
**Replies:** 0\
**Last updated:** [September 8, 2026, 12:22pm UTC](https://discourse.pymc.io/t/release-v6-3-2/17927 "2026-09-08T12:22:48Z")

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A new release of pymc is now available! :package: Release Information Version: v6.3.2 Repository: pymc-devs/pymc Release Page: Release v6.3.2 · pymc-devs/pymc · GitHub Note: It may take some time for the release to app…

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## [Setting and justifying priors for a discrete "what went wrong" model when I have no labeled data](https://discourse.pymc.io/t/setting-and-justifying-priors-for-a-discrete-what-went-wrong-model-when-i-have-no-labeled-data/17917)

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**Author:** [@ChiragG2101](https://discourse.pymc.io/u/ChiragG2101)\
**Replies:** 1\
**Last updated:** [September 3, 2026, 4:31pm UTC](https://discourse.pymc.io/t/setting-and-justifying-priors-for-a-discrete-what-went-wrong-model-when-i-have-no-labeled-data/17917 "2026-09-03T16:31:38Z")

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I’m modeling a data-quality decision as a small discrete belief problem and would love a sanity check from people who do this properly (I’m a software engineer, newer to Bayesian methods). For each scraped product-spe…

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## [Small-N Bayesian Poisson regression, sign flip on leave-one-out — sanity check on approach?](https://discourse.pymc.io/t/small-n-bayesian-poisson-regression-sign-flip-on-leave-one-out-sanity-check-on-approach/17921)

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**Author:** [@Alex25](https://discourse.pymc.io/u/Alex25)\
**Replies:** 2\
**Last updated:** [August 30, 2026, 3:10pm UTC](https://discourse.pymc.io/t/small-n-bayesian-poisson-regression-sign-flip-on-leave-one-out-sanity-check-on-approach/17921 "2026-08-30T15:10:03Z")

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Working on a small applied project: testing whether a technical “readiness” score for e-commerce vendors predicts how often an LLM agent mentions them in purchase-recommendation queries. Poisson regression, mentions ~ No…

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## [Founding Principal AI Research Scientist — NEST (probabilistic world models, remote)](https://discourse.pymc.io/t/founding-principal-ai-research-scientist-nest-probabilistic-world-models-remote/17891)

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**Author:** [@Martin\_Wainstein](https://discourse.pymc.io/u/Martin_Wainstein)\
**Replies:** 1\
**Last updated:** [August 20, 2026, 4:09pm UTC](https://discourse.pymc.io/t/founding-principal-ai-research-scientist-nest-probabilistic-world-models-remote/17891 "2026-08-20T16:09:32Z")

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We’re hiring a founding Principal AI Research Scientist for NEST (Open Earth Foundation —openearth.org—, with IIASA, Imperial, CEU & the Active Inference Institute, supported by Schmidt Sciences) to define an architectur…

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## [Bug in nutpie+numba: memory needed for LogNormal compilation scales superlinearly](https://discourse.pymc.io/t/bug-in-nutpie-numba-memory-needed-for-lognormal-compilation-scales-superlinearly/17911)

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**Author:** [@bridgeland](https://discourse.pymc.io/u/bridgeland)\
**Replies:** 4\
**Last updated:** [August 17, 2026, 3:34pm UTC](https://discourse.pymc.io/t/bug-in-nutpie-numba-memory-needed-for-lognormal-compilation-scales-superlinearly/17911 "2026-08-17T15:34:29Z")

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I discovered a bug in nutpie compilation. A model that conditions a LogNormal consumes far more memory in nutpie compilation than an otherwise identical model that conditions a Gamma. The ratio of memory usage between Lo…

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## [🚀 Release v6.3.1](https://discourse.pymc.io/t/release-v6-3-1/17910)

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**Author:** [@pymc-bot](https://discourse.pymc.io/u/pymc-bot)\
**Replies:** 0\
**Last updated:** [August 16, 2026, 9:03am UTC](https://discourse.pymc.io/t/release-v6-3-1/17910 "2026-08-16T09:03:19Z")

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A new release of pymc is now available! :package: Release Information Version: v6.3.1 Repository: pymc-devs/pymc Release Page: Release v6.3.1 · pymc-devs/pymc · GitHub Note: It may take some time for the release to app…

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## [Support symbolic eta parameter in LKJCholeskyCov.logp](https://discourse.pymc.io/t/support-symbolic-eta-parameter-in-lkjcholeskycov-logp/17909)

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**Author:** [@Ray729](https://discourse.pymc.io/u/Ray729)\
**Replies:** 2\
**Last updated:** [August 15, 2026, 6:21pm UTC](https://discourse.pymc.io/t/support-symbolic-eta-parameter-in-lkjcholeskycov-logp/17909 "2026-08-15T18:21:31Z")

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Hi everyone, I came across an open TODO in pymc/distributions/multivariate.py (around line 1297) for \_LKJCholeskyCovRV\_logp. # TODO: \_lkj\_normalizing\_constant currently requires \`eta\` and \`n\` to be constants try: e…

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## [🚀 Release v6.3.0](https://discourse.pymc.io/t/release-v6-3-0/17906)

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**Author:** [@pymc-bot](https://discourse.pymc.io/u/pymc-bot)\
**Replies:** 0\
**Last updated:** [August 12, 2026, 8:23am UTC](https://discourse.pymc.io/t/release-v6-3-0/17906 "2026-08-12T08:23:17Z")

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A new release of pymc is now available! :package: Release Information Version: v6.3.0 Repository: pymc-devs/pymc Release Page: Release v6.3.0 · pymc-devs/pymc · GitHub Note: It may take some time for the release to app…

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## [PyMC4 improvements over PyMC3](https://discourse.pymc.io/t/pymc4-improvements-over-pymc3/2362)

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**Author:** [@simon\_o](https://discourse.pymc.io/u/simon_o)\
**Replies:** 2\
**Last updated:** [August 11, 2026, 8:35pm UTC](https://discourse.pymc.io/t/pymc4-improvements-over-pymc3/2362 "2026-08-11T20:35:51Z")

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Forgive me if that has already been addressed, but is there some documentation that summarizes the expected/targeted improvements of PyMC4 over PyMC3? What are the main motivations/ideas behind PyMC4?Just curious.

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## [New contributor looking to get started — background in ML/RAG research](https://discourse.pymc.io/t/new-contributor-looking-to-get-started-background-in-ml-rag-research/17889)

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**Author:** [@Lakshya\_Pandey](https://discourse.pymc.io/u/Lakshya_Pandey)\
**Replies:** 3\
**Last updated:** [August 8, 2026, 6:23pm UTC](https://discourse.pymc.io/t/new-contributor-looking-to-get-started-background-in-ml-rag-research/17889 "2026-08-08T18:23:27Z")

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Hi everyone :waving\_hand: I’m Lakshya, a B.Tech CSE (AI & ML) student. I currently work as an AI Research Contributor at MIT CSAIL (Mantis AI, under Prof. Manolis Kellis) and also contribute to terrierteam/pyterrier\_rag…

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## [Hi everyone + question about repetitive PRs](https://discourse.pymc.io/t/hi-everyone-question-about-repetitive-prs/17905)

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**Author:** [@Ray729](https://discourse.pymc.io/u/Ray729)\
**Replies:** 2\
**Last updated:** [August 7, 2026, 3:34pm UTC](https://discourse.pymc.io/t/hi-everyone-question-about-repetitive-prs/17905 "2026-08-07T15:34:17Z")

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Hi all! I’m Ray, a CS student new to OSS contribution, and super excited to be joining this community. I did have one small question: if I’m working on maintenance changes, such as issue #6408 which requires multi file c…

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## [Priors, begginer questions and Titanic Data](https://discourse.pymc.io/t/priors-begginer-questions-and-titanic-data/17892)

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**Author:** [@Pegguins](https://discourse.pymc.io/u/Pegguins)\
**Replies:** 1\
**Last updated:** [July 31, 2026, 6:00pm UTC](https://discourse.pymc.io/t/priors-begginer-questions-and-titanic-data/17892 "2026-07-31T18:00:47Z")

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Hello, Apologies for the likely common and oft repeated prior quandary. I’ve been reading through the excellent examples, questions here, and articles such as this one by the Stan team: Prior Choice Recommendations · st…

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## [🚀 Release pymc-extras v0.14.0](https://discourse.pymc.io/t/release-pymc-extras-v0-14-0/17900)

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**Author:** [@pymc-bot](https://discourse.pymc.io/u/pymc-bot)\
**Replies:** 0\
**Last updated:** [July 28, 2026, 8:58pm UTC](https://discourse.pymc.io/t/release-pymc-extras-v0-14-0/17900 "2026-07-28T20:58:18Z")

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A new release of pymc-extras is now available! :package: Release Information Version: v0.14.0 Repository: pymc-devs/pymc-extras Release Page: Release v0.14.0 · pymc-devs/pymc-extras · GitHub Note: It may take some time…

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## [Regarding GSOC 2027 and PyMC projects](https://discourse.pymc.io/t/regarding-gsoc-2027-and-pymc-projects/17896)

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**Author:** [@Somil\_Gupta](https://discourse.pymc.io/u/Somil_Gupta)\
**Replies:** 0\
**Last updated:** [July 28, 2026, 2:36pm UTC](https://discourse.pymc.io/t/regarding-gsoc-2027-and-pymc-projects/17896 "2026-07-28T14:36:42Z")

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Hi Somil Gupta here , I am a Computer science and Applied Mathematics Undergrad at IIIT Delhi . I am interested in the project named " Linear Algebra Rewrites " and was wondering what is it’s current state and if it is …

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## [Online bayesian smoothing for streaming state space models](https://discourse.pymc.io/t/online-bayesian-smoothing-for-streaming-state-space-models/17883)

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**Author:** [@Dhairya](https://discourse.pymc.io/u/Dhairya)\
**Replies:** 2\
**Last updated:** [July 24, 2026, 7:21pm UTC](https://discourse.pymc.io/t/online-bayesian-smoothing-for-streaming-state-space-models/17883 "2026-07-24T19:21:44Z")

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hi all, and especially @jessegrabowski (following up on PR #8333!) a couple of weeks back i made a regime switching volatility stress tester using 100k synthetic equity tick returns to check out PR #8333 for the new str…

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## [🚀 Release v6.2.0](https://discourse.pymc.io/t/release-v6-2-0/17887)

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**Author:** [@pymc-bot](https://discourse.pymc.io/u/pymc-bot)\
**Replies:** 0\
**Last updated:** [July 23, 2026, 2:22pm UTC](https://discourse.pymc.io/t/release-v6-2-0/17887 "2026-07-23T14:22:10Z")

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A new release of pymc is now available! :package: Release Information Version: v6.2.0 Repository: pymc-devs/pymc Release Page: Release v6.2.0 · pymc-devs/pymc · GitHub Note: It may take some time for the release to app…

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## [Arviz Issues following Tutorials](https://discourse.pymc.io/t/arviz-issues-following-tutorials/17874)

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**Author:** [@Pegguins](https://discourse.pymc.io/u/Pegguins)\
**Replies:** 2\
**Last updated:** [July 21, 2026, 8:34am UTC](https://discourse.pymc.io/t/arviz-issues-following-tutorials/17874 "2026-07-21T08:34:07Z")

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Hi. I’ve been trying to follow along the data containers tutorial: Using Data Containers — PyMC example gallery To try understand the data structures and model specification better. (I’m only used to using the R style …

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## [Dynamic occupancy model with pymc\_extras](https://discourse.pymc.io/t/dynamic-occupancy-model-with-pymc-extras/17436)

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**Author:** [@philpatton](https://discourse.pymc.io/u/philpatton)\
**Replies:** 16\
**Last updated:** [July 19, 2026, 8:53pm UTC](https://discourse.pymc.io/t/dynamic-occupancy-model-with-pymc-extras/17436 "2026-07-19T20:53:51Z")

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Good afternoon! I’m writing to see if y’all think that this dynamic occupancy model would be a good fit for DiscreteMarkovChain and marginalize in the PyMC Extras package. In this model, we detect animals at occupied, z…

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## [🚀 Release pymc-extras v0.13.1](https://discourse.pymc.io/t/release-pymc-extras-v0-13-1/17882)

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**Author:** [@pymc-bot](https://discourse.pymc.io/u/pymc-bot)\
**Replies:** 0\
**Last updated:** [July 19, 2026, 8:53pm UTC](https://discourse.pymc.io/t/release-pymc-extras-v0-13-1/17882 "2026-07-19T20:53:48Z")

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A new release of pymc-extras is now available! :package: Release Information Version: v0.13.1 Repository: pymc-devs/pymc-extras Release Page: Release v0.13.1 · pymc-devs/pymc-extras · GitHub Note: It may take some time…

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## [Media Mix Modelling](https://discourse.pymc.io/t/media-mix-modelling/17877)

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**Author:** [@nitasce](https://discourse.pymc.io/u/nitasce)\
**Replies:** 3\
**Last updated:** [July 19, 2026, 8:00am UTC](https://discourse.pymc.io/t/media-mix-modelling/17877 "2026-07-19T08:00:54Z")

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Hi folks, i have a few questions about implementing mmm. How do you know which function to choose for saturation curve? How do you know which interaction terms to include in mmm?

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## [Pymc\_forecast — a new Bayesian time-series forecasting toolkit for PyMC](https://discourse.pymc.io/t/pymc-forecast-a-new-bayesian-time-series-forecasting-toolkit-for-pymc/17873)

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**Author:** [@twiecki](https://discourse.pymc.io/u/twiecki)\
**Replies:** 1\
**Last updated:** [July 17, 2026, 6:40pm UTC](https://discourse.pymc.io/t/pymc-forecast-a-new-bayesian-time-series-forecasting-toolkit-for-pymc/17873 "2026-07-17T18:40:17Z")

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Hi all, we just released pymc\_forecast, a toolkit for Bayesian time-series forecasting with PyMC. The philosophy: you write the generative model, the package handles everything around it — the train/forecast plumbing, i…

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## [🚀 Release pymc-extras v0.13.0](https://discourse.pymc.io/t/release-pymc-extras-v0-13-0/17872)

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**Author:** [@pymc-bot](https://discourse.pymc.io/u/pymc-bot)\
**Replies:** 0\
**Last updated:** [July 13, 2026, 1:46pm UTC](https://discourse.pymc.io/t/release-pymc-extras-v0-13-0/17872 "2026-07-13T13:46:50Z")

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A new release of pymc-extras is now available! :package: Release Information Version: v0.13.0 Repository: pymc-devs/pymc-extras Release Page: Release v0.13.0 · pymc-devs/pymc-extras · GitHub Note: It may take some time…

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## [Hidden Markov Models in PyMC: marginalize and recover a DiscreteMarkovChain](https://discourse.pymc.io/t/hidden-markov-models-in-pymc-marginalize-and-recover-a-discretemarkovchain/17871)

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**Author:** [@ricardoV94](https://discourse.pymc.io/u/ricardoV94)\
**Replies:** 0\
**Last updated:** [July 13, 2026, 6:45am UTC](https://discourse.pymc.io/t/hidden-markov-models-in-pymc-marginalize-and-recover-a-discretemarkovchain/17871 "2026-07-13T06:45:25Z")

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Latest PyMC example: Hidden Markov Models in PyMC: marginalize and recover a DiscreteMarkovChain — PyMC example gallery

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## [TypeError: Real.grad illegally returned an integer-valued variable - when pm.sample](https://discourse.pymc.io/t/typeerror-real-grad-illegally-returned-an-integer-valued-variable-when-pm-sample/17870)

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**Author:** [@thejasvibr](https://discourse.pymc.io/u/thejasvibr)\
**Replies:** 2\
**Last updated:** [July 12, 2026, 6:07pm UTC](https://discourse.pymc.io/t/typeerror-real-grad-illegally-returned-an-integer-valued-variable-when-pm-sample/17870 "2026-07-12T18:07:42Z")

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HI All, I’m trying to estimate how much a mic array has been shifted using experimental measurements. Modelling the measured mic-to-mic distances for a few of the mics in the whole array - I try to check how much each …

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## [Hierarchical model with copula on GPU: NumPyro or nutpie using PyMC 5.19?](https://discourse.pymc.io/t/hierarchical-model-with-copula-on-gpu-numpyro-or-nutpie-using-pymc-5-19/17853)

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**Author:** [@user-jiyichen](https://discourse.pymc.io/u/user-jiyichen)\
**Replies:** 3\
**Last updated:** [July 9, 2026, 2:25pm UTC](https://discourse.pymc.io/t/hierarchical-model-with-copula-on-gpu-numpyro-or-nutpie-using-pymc-5-19/17853 "2026-07-09T14:25:45Z")

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My compute cluster only supports PyMC 5.19 using Python 3.12.4, and I need to fit a bivariate joint model with copulas and two quite complicated marginal models (~2k parameters). It took ~5 hours for 5k warmups + 5k ite…

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## [🚀 Release v6.1.0](https://discourse.pymc.io/t/release-v6-1-0/17869)

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**Author:** [@pymc-bot](https://discourse.pymc.io/u/pymc-bot)\
**Replies:** 0\
**Last updated:** [July 7, 2026, 10:17am UTC](https://discourse.pymc.io/t/release-v6-1-0/17869 "2026-07-07T10:17:15Z")

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A new release of pymc is now available! :package: Release Information Version: v6.1.0 Repository: pymc-devs/pymc Release Page: Release v6.1.0 · pymc-devs/pymc · GitHub Note: It may take some time for the release to app…

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