# \#smc

**URL:** https://discourse.pymc.io/tag/smc/79.md

[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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## [Parallelization of Sequential Monte Carlo: sample\_smc](https://discourse.pymc.io/t/parallelization-of-sequential-monte-carlo-sample-smc/17712)

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**Author:** [@janwi](https://discourse.pymc.io/u/janwi)\
**Replies:** 1\
**Last updated:** [May 15, 2026, 6:41am UTC](https://discourse.pymc.io/t/parallelization-of-sequential-monte-carlo-sample-smc/17712 "2026-05-15T06:41:30Z")

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Hello everyone, I am new to PyMC and I am planning to use the SMC sampler, pm.sample\_smc, for Bayesian parameter calibration. For example: pm.sample\_smc(draws=1000, chains=1, cores=1) One attractive feature of SMC me…

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## [Dimension error while replicating the Lotka Volterra model example](https://discourse.pymc.io/t/dimension-error-while-replicating-the-lotka-volterra-model-example/16224)

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**Author:** [@maerad](https://discourse.pymc.io/u/maerad)\
**Replies:** 4\
**Last updated:** [April 29, 2026, 12:58am UTC](https://discourse.pymc.io/t/dimension-error-while-replicating-the-lotka-volterra-model-example/16224 "2026-04-29T00:58:24Z")

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I’m trying to replicate the Lotka Volterra example in the Approximate Bayesian Computation section, and find that I’m getting an dimension mismatch error. Specifically, while running the sample() method, I get RuntimeE…

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## [SMC kernel index out of bounds](https://discourse.pymc.io/t/smc-kernel-index-out-of-bounds/17490)

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**Author:** [@vian](https://discourse.pymc.io/u/vian)\
**Replies:** 4\
**Last updated:** [December 23, 2025, 8:26am UTC](https://discourse.pymc.io/t/smc-kernel-index-out-of-bounds/17490 "2025-12-23T08:26:46Z")

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Hi there, I came across an issue with the following function in smc/kernels.py. I’m trying to figure out a minimal example but what I can say for now is that I have an index out of bounds for idx for weight\_accu += wei…

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## [Split draws in SMC into different chains](https://discourse.pymc.io/t/split-draws-in-smc-into-different-chains/17481)

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**Author:** [@argihbfwy](https://discourse.pymc.io/u/argihbfwy)\
**Replies:** 2\
**Last updated:** [December 12, 2025, 8:55am UTC](https://discourse.pymc.io/t/split-draws-in-smc-into-different-chains/17481 "2025-12-12T08:55:09Z")

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Hi! I’m using the PYMC SMC for a modeling task where each iteration is quite expensive. The documentation recommends 2000 draws, but I’m wondering: can I split this into 8 chains with 250 draws each to speed things up? O…

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## [Simulator params with different shapes](https://discourse.pymc.io/t/simulator-params-with-different-shapes/16882)

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**Author:** [@claire](https://discourse.pymc.io/u/claire)\
**Replies:** 1\
**Last updated:** [April 23, 2025, 9:04pm UTC](https://discourse.pymc.io/t/simulator-params-with-different-shapes/16882 "2025-04-23T21:04:41Z")

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I am using sample\_smc to find the parameters of a black-box function using a Simulator RV. The parameters to the simulator function have different shapes, but when I try to do this is causes a numpy broadcast error. Thi…

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## [How can I deal with a computationally expensive simulator method in Sequential Monte Carlo/Approximate Bayesian Computation?](https://discourse.pymc.io/t/how-can-i-deal-with-a-computationally-expensive-simulator-method-in-sequential-monte-carlo-approximate-bayesian-computation/11602)

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**Author:** [@lumax](https://discourse.pymc.io/u/lumax)\
**Replies:** 16\
**Last updated:** [October 24, 2024, 5:58pm UTC](https://discourse.pymc.io/t/how-can-i-deal-with-a-computationally-expensive-simulator-method-in-sequential-monte-carlo-approximate-bayesian-computation/11602 "2024-10-24T17:58:59Z")

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I want to do Bayesian Inference of parameters of a black-box simulator function. The issue is that the simulator is very slow, taking many seconds or minutes for a single evaluation of the model at some parameters. Limit…

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## [Modeling a Spectrum of Gaussians with SMC](https://discourse.pymc.io/t/modeling-a-spectrum-of-gaussians-with-smc/14854)

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**Author:** [@tvwenger](https://discourse.pymc.io/u/tvwenger)\
**Replies:** 11\
**Last updated:** [August 5, 2024, 5:26pm UTC](https://discourse.pymc.io/t/modeling-a-spectrum-of-gaussians-with-smc/14854 "2024-08-05T17:26:54Z")

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Here is yet another spectrum of Gaussians question… I am attempting to fit a spectrum of Gaussians. Eventually, I aim to determine the number of Gaussian components using model selection. Eventually, the order of the Ga…

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## [SMC; Random walk; Adding z dimension results in bias in x dimension](https://discourse.pymc.io/t/smc-random-walk-adding-z-dimension-results-in-bias-in-x-dimension/14311)

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**Author:** [@r2keks2](https://discourse.pymc.io/u/r2keks2)\
**Replies:** 0\
**Last updated:** [April 22, 2024, 3:37pm UTC](https://discourse.pymc.io/t/smc-random-walk-adding-z-dimension-results-in-bias-in-x-dimension/14311 "2024-04-22T15:37:26Z")

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Hello, I had the same bug with the Metropolis sampler, which was solved by updating to v5.6.1. Now i want to use SMC. Here I simplified my problem as much as possible. I want to sample a random walker that takes N s…

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## [SMC Sampler references](https://discourse.pymc.io/t/smc-sampler-references/13657)

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**Author:** [@jucor](https://discourse.pymc.io/u/jucor)\
**Replies:** 6\
**Last updated:** [January 22, 2024, 7:44pm UTC](https://discourse.pymc.io/t/smc-sampler-references/13657 "2024-01-22T19:44:56Z")

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Hi PyMC team, and in particular @ricardoV94 @aloctavodia @junpenglao who seem to have worked a lot on the SMC module I was thrilled to find a SMC sampler implementation in a proper established package. I was wondering,…

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## [Options for SMC](https://discourse.pymc.io/t/options-for-smc/13220)

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**Author:** [@mike-lawrence](https://discourse.pymc.io/u/mike-lawrence)\
**Replies:** 3\
**Last updated:** [December 5, 2023, 12:50pm UTC](https://discourse.pymc.io/t/options-for-smc/13220 "2023-12-05T12:50:49Z")

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I’m new to SMC and encountering high rhats when using default settings on a particular model. What knobs would folks suggest playing with to attempt to resolve this? If using MCMC, I’d expand the warmup period and mess w…

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## [Keyword in sample\_smc](https://discourse.pymc.io/t/keyword-in-sample-smc/9686)

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**Author:** [@jiayuand](https://discourse.pymc.io/u/jiayuand)\
**Replies:** 8\
**Last updated:** [June 22, 2022, 5:40am UTC](https://discourse.pymc.io/t/keyword-in-sample-smc/9686 "2022-06-22T05:40:09Z")

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I am currently updating pymc3 to pymc, when using pm.sample\_smc(XXX, nsteps = 50), it turns out that TypeError: SMC\_KERNEL.init() got an unexpected keyword argument ‘nsteps’. May I know how to get this solved? Thanks!

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## [Does PyMC work for ABC SMC?](https://discourse.pymc.io/t/does-pymc-work-for-abc-smc/8798)

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**Author:** [@fsosa](https://discourse.pymc.io/u/fsosa)\
**Replies:** 13\
**Last updated:** [May 6, 2022, 2:27pm UTC](https://discourse.pymc.io/t/does-pymc-work-for-abc-smc/8798 "2022-05-06T14:27:15Z")

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Hi everyone, I’m new here and new to Bayesian modeling. I’m working on something that involves approximate bayesian inference with a physics engine (the physics engine is the simulator). Is it possible to use PyMC to per…

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## [Aesara aeppl.logprob.ParameterValueError](https://discourse.pymc.io/t/aesara-aeppl-logprob-parametervalueerror/9274)

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**Author:** [@vian](https://discourse.pymc.io/u/vian)\
**Replies:** 1\
**Last updated:** [April 25, 2022, 12:36pm UTC](https://discourse.pymc.io/t/aesara-aeppl-logprob-parametervalueerror/9274 "2022-04-25T12:36:01Z")

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Hi there, I’m trying to update my script which uses 3.11.4 to 3.11.5 and ran into two issues: ERROR (aesara.graph.opt): Optimization failure due to: transform\_values Optimization failure due to: transform\_values ERR…

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## [SMC chains with multiple modes](https://discourse.pymc.io/t/smc-chains-with-multiple-modes/8992)

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**Author:** [@vian](https://discourse.pymc.io/u/vian)\
**Replies:** 2\
**Last updated:** [March 10, 2022, 9:51am UTC](https://discourse.pymc.io/t/smc-chains-with-multiple-modes/8992 "2022-03-10T09:51:24Z")

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Hi there, In the cases I run, with high dimensionality, it happens often that the individual SMC chains seem to probe only a very limited mode/part of the parameter space (see attached). I tried to increase the acceptan…