Install rethinking


 * 1) Install rethinking
 * 2) Test rethinking
 * 3) Workaround to fit rethinking models directly in Stan
 * 1) Workaround to fit rethinking models directly in Stan
 * 1) Workaround to fit rethinking models directly in Stan

precis(fit_stan)
 * 1) Precis of fit

Also see https://roadfiresoftware.com/2017/09/how-to-install-multiple-versions-of-xcode-at-the-same-time/
 * May need different version of command line tools & gfortran? https://cran.r-project.org

Not experiencing any issues with rstan. Those models are fitting without problem. But no Stan-based models are working for rethinking!!!
 * Unistall r development toolchain: https://thecoatlessprofessor.com/programming/r/uninstalling-the-r-development-toolchain-on-macos/

Instructions for installing R compiler tools for Rcpp on macOS: https://thecoatlessprofessor.com/programming/cpp/r-compiler-tools-for-rcpp-on-macos/.

Am I using the right versions of clang and gfortran for R 4.0? See https://cran.r-project.org. Seems weird that the ones I'm using would work with rstan but not rethinking, since rstan is the backend.


 * Compiler optimization recommended here: https://github.com/stan-dev/rstan/wiki/Configuring-C---Toolchain-for-Mac. This involves entering the following at the R command prompt: