# Using the wiener\_lpdf() function in the cmdstanr package to implement a diffusion model, the construction of a Markov chain was unsuccessful

**URL:** <https://discourse.mc-stan.org/t/using-the-wiener-lpdf-function-in-the-cmdstanr-package-to-implement-a-diffusion-model-the-construction-of-a-markov-chain-was-unsuccessful/35213>\
**Category:** CmdStan\
**Created:** [May 21, 2024, 10:26am UTC](https://discourse.mc-stan.org/t/using-the-wiener-lpdf-function-in-the-cmdstanr-package-to-implement-a-diffusion-model-the-construction-of-a-markov-chain-was-unsuccessful/35213 "2024-05-21T10:26:07Z")\
**Posts on this page:** 1\
**Showing post:** 6

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**Author:** ![WardBrian](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/wardbrian/32/12078_2.png) [@WardBrian](https://discourse.mc-stan.org/u/WardBrian)\
**Post date:** [May 23, 2024, 1:32pm UTC](https://discourse.mc-stan.org/t/using-the-wiener-lpdf-function-in-the-cmdstanr-package-to-implement-a-diffusion-model-the-construction-of-a-markov-chain-was-unsuccessful/35213/6 "2024-05-23T13:32:32Z")

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Hi @jlb -

We just released [another round of release candidates](https://discourse.mc-stan.org/t/cmdstan-stan-2-35-release-candidate/35133/18) which include a fix for the error you were receiving here.

Thanks for helping test out new features!

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_[View the full topic](https://discourse.mc-stan.org/t/using-the-wiener-lpdf-function-in-the-cmdstanr-package-to-implement-a-diffusion-model-the-construction-of-a-markov-chain-was-unsuccessful/35213)._