Advice to Those Installing REBayes The REBayes package is available from CRAN. However, unlike most R packages it requires some further installation actions. In an ideal world, CRAN would automagically install the Rmosek package as well. Installation of dependencies usually work fine, but Rmosek requires some tweaking at install time. Rmosek is an interface to the Mosek environment of Erling Andersen. You should install Mosek first, along with its license file before trying to use REBayes. Rmosek is now available from CRAN so it can be installed with the usual invocation of install.packages("Rmosek"), however the version of the Rmosek package available on CRAN is really just a skeleton intended to facilitate installation of the real Rmosek package from the Mosek website; the advantage of this over prior schemes is that it automates the configuration and ensures that the Rmosek setup is compatible with the installed version of Mosek. After installing Rmosek from CRAN the following steps should be taken: library(Rmosek) mosek_attachbuilder() install.rmosek() #this installs a version of rmosek replacing the CRAN one then it is recommended to quit the R session, restart R and try library(Rmosek) example(mosek) This should produce output for a trivial example. The academic license for Mosek is freely downloadable from https://www.mosek.com/products/academic-license and is good for one year. Just fill in the form and then via email you get a license file (mosek.lic) that needs to be moved to the appropriate place in the mosek directory. This used to be into the subdirectory licenses, but since version 7 it belongs in MOSEKHOME. Of course you need to verify that the mosek executable is in your path: try mosek from the shell command line to check this. It used to be necessary to define the location of the license file as a shell variable but this no longer seems necessary either. Once mosek is installed, the next step is to install the R package Rmosek. Installation instructions and other documentation for Rmosek is available at https://docs.mosek.com/8.1/rmosek/index.html. Now install REBayes also from CRAN (or source) and all should be well, to test you might try as an initial step: require(REBayes) demo(GLmix1) Considerable further detail is available from the mosek and Rmosek documentation. And the vignettes for the REBayes package. These instructions should work for any installed version of Mosek, in particular most of the REBayes code was developed for Mosek V8, however Mosek V9 is now available in betatest and limited testing has confirmed that this is typically more efficient. See https://themosekblog.blogspot.co.uk/2018/01/version-9-roadmap_31.html