Gfortran is very nice, but I recommend a recent version (at least ver >= 7) rather than old versions (e.g. ver 4.4, which may still be the default on CentOS 6 e

Gfortran is very nice, but I recommend a recent version (at least ver >= 7) rather than old versions (e.g. ver 4.4, which may still be the default on CentOS 6 etc). For performance, I guess Intel fortran is probably better (but also depends on calculations).