gem install gsl ERROR: Error installing gsl: ERROR: Failed to build gem native extension. /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb extconf.rb:1: command not found: gsl-config --version *** extconf.rb failed *** Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers. Check the mkmf.log file for more details. You may need configuration options.
gsl from http://ossm.utm.my/gnu/gsl/gsl-1.15.tar.gz. extract. run these command
cd gsl ./configure make clean make sudo make install
and last, reinstall the gem
sudo gem install gsl
if error said that ruby need gsl-x.x, then you should download gsl with same or lower version. for example required gsl version is 1.15.3, it's mean that you must download gsl v 1.15.3 or 1.15