OS X package installation depends on gfortran-4.8

Type these two lines in your terminal, direct quote:

curl -O http://r.research.att.com/libs/gfortran-4.8.2-darwin13.tar.bz2
sudo tar fvxj gfortran-4.8.2-darwin13.tar.bz2 -C /

It will download you the gfortran for Mavericks (which is missing in your system at the moment) and will install it in your system. At least, this solved the same problem for me

(I'm running late 2011 MacPro, Mavericks).

Edit: I now think this is best accomplished using Homebrew:

brew reinstall gcc48 --with-fortran

While I think the following procedure will work, it is not as clean. However, I still recommend configuring ~/.R/Makevars as described below.

To build on the answer by @TheBigMike, I used the following procedure to install gfortran-4.8 alongside homebrew, and then configured R to select this fortran compiler.

First, download and unpack gfortran 4.8:

su admin
curl -O http://r.research.att.com/libs/gfortran-4.8.2-darwin13.tar.bz2
mkdir /tmp/gfortran
tar fvxz gfortran-4.8.2-darwin13.tar.bz2 -C /tmp/gfortran

Delete the gfortran file alias that interferes with homebrew:

rm /tmp/gfortran/usr/local/bin/gfortran

Install gfortran 4.8

cp -r /tmp/gfortran/usr/local/ /usr/local

To tell R to use gfortran 4.8, create a file called ~/.R/Makevars:

mkdir -p ~/.R
touch ~/.R/Makevars

Put the following into ~/.R/Makevars:

FLIBS=""
F77="gfortran-4.8"
FC="gfortran-4.8"

Now restart R. Once R has been restarted, any packages that depend upon fortran 4.8 should now work. homebrew should be undisturbed.