# Convert from var-cov matrix to correlation matrix

**URL:** <https://discourse.mc-stan.org/t/convert-from-var-cov-matrix-to-correlation-matrix/29483>\
**Category:** Modeling\
**Created:** [November 15, 2022, 6:12pm UTC](https://discourse.mc-stan.org/t/convert-from-var-cov-matrix-to-correlation-matrix/29483 "2022-11-15T18:12:26Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![CerulloE](https://yyz2.discourse-cdn.com/flex030/user_avatar/discourse.mc-stan.org/cerulloe/32/15968_2.png) [@CerulloE](https://discourse.mc-stan.org/u/CerulloE)\
**Post date:** [November 15, 2022, 6:12pm UTC](https://discourse.mc-stan.org/t/convert-from-var-cov-matrix-to-correlation-matrix/29483/1 "2022-11-15T18:12:26Z")

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Hi,

Is there a function in Stan to convert a variance-covariance matrix to a correlation matrix?

Thanks

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<div class="post-metadata">

**Author:** ![spinkney](https://avatars.discourse-cdn.com/v4/letter/s/dec6dc/32.png) [@spinkney](https://discourse.mc-stan.org/u/spinkney)\
**Post date:** [November 15, 2022, 9:02pm UTC](https://discourse.mc-stan.org/t/convert-from-var-cov-matrix-to-correlation-matrix/29483/2 "2022-11-15T21:02:10Z")

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> [@Averaging generated covariance matrices](https://discourse.mc-stan.org/t/averaging-generated-covariance-matrices/23944/11):
>
> Same thing but faster matrix cov2cor(matrix V) { int p = rows(V); vector[p] Is = inv\_sqrt(diagonal(V)); return quad\_form\_diag(V, Is); }