# Possible Error in the Correlation Matrices (10.9) Section of the Stan Manual

**URL:** <https://discourse.mc-stan.org/t/possible-error-in-the-correlation-matrices-10-9-section-of-the-stan-manual/29671>\
**Category:** General\
**Created:** [December 1, 2022, 10:55pm UTC](https://discourse.mc-stan.org/t/possible-error-in-the-correlation-matrices-10-9-section-of-the-stan-manual/29671 "2022-12-01T22:55:47Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![hhau](https://avatars.discourse-cdn.com/v4/letter/h/2bfe46/32.png) [@hhau](https://discourse.mc-stan.org/u/hhau)\
**Post date:** [December 2, 2022, 5:43pm UTC](https://discourse.mc-stan.org/t/possible-error-in-the-correlation-matrices-10-9-section-of-the-stan-manual/29671/3 "2022-12-02T17:43:08Z")

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This has come up before:

- [Incorrect formula for correlation matrix transform](https://discourse.mc-stan.org/t/incorrect-formula-for-correlation-matrix-transform/24664)
- [LKJ inverse transform for correlation matrices (incorrect documentation?)](https://discourse.mc-stan.org/t/lkj-inverse-transform-for-correlation-matrices-incorrect-documentation/19312)

I think I even said I would get to the bottom of it in the first link (I definitely did not and then forgot about it, whoops). I am more confident in the formulae in 10.12: [10.12 Cholesky factors of correlation matrices | Stan Reference Manual](https://mc-stan.org/docs/reference-manual/cholesky-factors-of-correlation-matrices-1.html), and would then take the crossproduct of the result to get a correlation matrix.

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