The only gfortran that seems to be compatible with Yosemite is on the HPC site. You will link to this site when you select the Download button on the
previous page. When there, download the gcc-5.0-bin.tar.gz file, and type the following into your terminal: gunzip gcc-5.0-bin.tar.gz, and then
sudo tar -xvf gcc-5.0-bin.tar -C /. The HPC webpage has instructions but gives these commands for version 4.9.
Pmetrics automatically checks data files for errors before running. It uses the rJava package for this. rJava may cause your R session
to abort. If so, download and install this version of Java, which works well with Yosemite.
Make sure you have R version 3.1.2 or later and Pmetrics version 1.3.0 or later.