in reply to
Re^2: Install Math::GSL fail
in thread Install Math::GSL fail
GSL does not appear in /usr/local/pkgconfig, but it is installed
Maybe you need to install the respective *-dev package for the GSL library (?)
Not entirely sure about Fedora, but most distros split their library packages into two parts: one for the runtime libs (always needed), and one for the "development stuff" (with the package name usually ending in "-dev" or "-devel"), like header files, static libs, the package config (".pc") file, etc., which are only needed if you build software that links against the library in question.