NMatrix is a Ruby library providing some linear algebra functions and sparse data-structures. Unfortunately, it's surprisingly difficult to get running on OSX. Here's a hackish method, using rvm and macports (I'll show what I had to install on my system, you may need more – the documentation is rather sparse at this point).
sudo port install atlas
cd rvm use ruby-1.9.3
gem install isolate hoe rspec rake-compiler hoe-git json packable git clone https://github.com/mohawkjohn/nmatrix.git
cd nmatrix
rake compile
sed -i "" 's:clang\\+\\+:g++ -I/opt/local/include:g' tmp/x86\_64-darwin11.3.0/nmatrix/1.9.3/Makefile
sed -i "" 's:clang:gcc -I/opt/local/include:g' tmp/x86\_64-darwin11.3.0/nmatrix/1.9.3/Makefile
sed -i "" 's:nmatrix\\.so:nmatrix\\.bundle:g' lib/nmatrix.rb
rake compile
rake compile
rake newb
cd nmatrix
ln nmatrix/nmatrix.bundle .
cd irb -I nmatrix/lib/
require 'nmatrix' Hopefully this process will improve soon (SciRuby has Google Summer of Code support this year), but this procedure should get you started. update: for debugging purposes, I'm running an up to date OSX 10.7.4 and macports (2.1.0), ruby-1.9.3-p125, clang version 3.1 (tags/Apple/clang-318.0.58).