installing R gsl package on Mac

I finally got this to work though I'm not sure which parts of the following are absolutely essential. Here's a step-by-step list of instructions:

(steps in parentheses may be optional. Perhaps the whole thing works with homebrew)

1. (download the latest version of the GSL from http://ftp.gnu.org/gnu/gsl/ (as of this writing the file to get is gsl-1.16.tar.gz))
2. (open up a terminal window, untar the file, cd into the directory and then run ./configure, make and make install)
3. download the sources to the R package from http://cran.r-project.org/web/packages/gsl/index.html
4. open up a terminal window and run launchctl setenv PATH "/usr/local/bin:$PATH"
5. in the same terminal window, build the R package (I couldn't get this to work from within R) by untar'ing the file just downloaded, cding into the directory and then running R CMD build ./gsl and R CMD INSTALL gsl_1.9-10.tar.gz

I was able to get things working (OS X Yosemite 10.10, R 3.1.1, gsl 1.16, gsl R package 1.9-10) with standard brew-installed R and gsl by manually prefixing CFLAGS and LDFLAGS with the output from gsl-config --cflags and gsl-config --libs respectively.

The following:

CFLAGS="-I/usr/local/opt/gsl/include" LDFLAGS="-L/usr/local/opt/gsl/lib -lgsl -lgslcblas" R
...
> install.packages("gsl")

worked for me.

Note that gsl-config lists the direct path to my Cellar, the paths above are brew symlinks.

For Mac, just run:

brew install gsl

then install the package in r