# Error message Eigen not found

**URL:** <https://discourse.mc-stan.org/t/error-message-eigen-not-found/14276>\
**Category:** General\
**Tags:** specification\
**Created:** [April 12, 2020, 8:22pm UTC](https://discourse.mc-stan.org/t/error-message-eigen-not-found/14276 "2020-04-12T20:22:44Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![rmbaskin](https://avatars.discourse-cdn.com/v4/letter/r/f6c823/32.png) [@rmbaskin](https://discourse.mc-stan.org/u/rmbaskin)\
**Post date:** [April 12, 2020, 8:22pm UTC](https://discourse.mc-stan.org/t/error-message-eigen-not-found/14276/1 "2020-04-12T20:22:44Z")

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rstan (Version 2.19.3, GitRev: 2e1f913d3ca3)

R version 3.6.1 (2019-07-05) – “Action of the Toes”  
Copyright (C) 2019 The R Foundation for Statistical Computing  
Platform: x86\_64-w64-mingw32/x64 (64-bit)

OS is Windows 10 Enterprise  
Version 1909 / OS build 18363.752

> library(RcppEigen)  
> Warning message:  
> package ‘RcppEigen’ was built under R version 3.6.3

I run the QR decomposition example from the Stan site on my Mac laptop and it runs without a problem. I do get the warning message about the Jacobian they say will happen.

I run the same code and data on a Windows desktop and get the error message that Eigen can’t be found:

> library(RcppEigen)  
> qr\_fit ← stan(file=‘qr\_regr.stan’, data=input\_data, seed=483892929)  
> DIAGNOSTIC(S) FROM PARSER:  
> Info:  
> Left-hand side of sampling statement (~) may contain a non-linear transform of a parameter or local variable.  
> If it does, you need to include a target += statement with the log absolute determinant of the Jacobian of the transform.  
> Left-hand-side of sampling statement:  
> beta ~ normal(…)

Error in stan\_model(file, model\_name = model\_name, model\_code = model\_code, :  
Eigen not found; call install.packages(‘RcppEigen’)

thanks for any help  
bob

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<div class="post-metadata">

**Author:** ![rmbaskin](https://avatars.discourse-cdn.com/v4/letter/r/f6c823/32.png) [@rmbaskin](https://discourse.mc-stan.org/u/rmbaskin)\
**Post date:** [April 12, 2020, 9:32pm UTC](https://discourse.mc-stan.org/t/error-message-eigen-not-found/14276/2 "2020-04-12T21:32:11Z")

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Nevermind - it was our security software protecting me from Stan  
sorry for this  
bob