On the cluster, the GNU Scientific Library (GSL) version 2.4 is installed.
The GNU Scientific Library is a collection of functions, written in C, for the purpose of numerical calculations (e.g routines for linear algebra and fast Fourier transforms). The complete documentation and feature list can be found here.
This command lists the installed files of the two packages
gsl-devel, which are installed on the login nodes:
$ rpm -ql gsl gsl-devel
On the compute nodes, only the package
gsl is available.