If GSL is installed correctly, then the executable gsl-config can be directly used to pick up the locations of the include headers and the library files. The additional, -Xlinker -rpath -Xlinker $(GSL_LIBDIR) simply embeds the library path used at compile time into the executable such that the library used at compile time is picked up at runtime (in the unusual circumstance that incompatible versions of GSL are installed and the ordering in (DY)LD_LIBRARY_PATH and PATH are flipped.
In case, gsl-config is not found in PATH, then the user has the ability to specify where gsl is located.
If
GSLis installed correctly, then the executablegsl-configcan be directly used to pick up the locations of the include headers and the library files. The additional,-Xlinker -rpath -Xlinker $(GSL_LIBDIR)simply embeds the library path used at compile time into the executable such that the library used at compile time is picked up at runtime (in the unusual circumstance that incompatible versions ofGSLare installed and the ordering in(DY)LD_LIBRARY_PATHandPATHare flipped.In case,
gsl-configis not found inPATH, then the user has the ability to specify wheregslis located.