Hello!
As I already stated in SciRuby/nmatrix#172 I'm the rpm-maintainer of rubygem-narray on Fedora and RHEL / CentOS.
As you can see in the quoted issue above, there are some issues with NArray / NMatrix installed / used within the same environment. I'd love to see some fix for this issue.
Unfortunately that issue also affects rb-gsl through dependency.
Cheers,
besser82