• rb-gsl
  Ruby interface to the GNU Scientific Library
  https://github.com/blackwinter/rb-gsl
  dependencies: GSL

• ruby-opencv
  OpenCV wrapper for Ruby
  https://github.com/ruby-opencv/ruby-opencv/
  dependencies: OpenCV

• classifier-reborn
  Bayesian and LSI classification
  https://github.com/jekyll/classifier-reborn
  dependencies: GSL

• decisiontree
  ID3-based implementation of the ML Decision Tree algorithm
  https://github.com/igrigorik/decisiontree
  dependencies: Graphviz

• similarity
  Calculate similarity between documents using TF-IDF weights
  https://github.com/bbcrd/Similarity
  dependencies: GSL

• rb-libsvm
  Ruby language bindings for LIBSVM
  https://github.com/febeling/rb-libsvm
  dependencies: None (LIBSVM is bundled with the project)

• ruby-fann
  Ruby library for interfacing with FANN (Fast Artificial Neural Network)
  https://github.com/tangledpath/ruby-fann
  dependencies: None (FANN is bundled with the project)

• tlearn-rb
  Recurrent Neural Network library for Ruby
  https://github.com/josephwilk/tlearn-rb
  http://blog.josephwilk.net/ruby/recurrent-neural-networks-in-ruby.html

• k_means
  Attempting to build a fast, memory efficient K-Means program
  https://github.com/reddavis/K-Means

• knn
  Simple K Nearest Neighbour Algorithm
  https://github.com/reddavis/knn

• distance_measures
  A bunch of distance measures that extend Array
  https://github.com/reddavis/Distance-Measures

• fast-stemmer
  Fast Porter stemmer based on a C version of the algorithm
  https://github.com/romanbsd/fast-stemmer

• statsample
  A suite for basic and advanced statistics on Ruby
  https://github.com/clbustos/statsample dependencies: GSL

• statistics2
  Provides normal, Chi-square, t- and F- probability distributions for Ruby
  https://github.com/abscondment/statistics2

• ruby-graphviz
  https://github.com/glejeune/Ruby-Graphviz
  dependencies: Graphviz

• rbgnuplot
  https://github.com/rdp/ruby_gnuplot/tree/master
  dependencies: Gnuplot

• GSL (GNU Scientific Library)
  http://www.gnu.org/software/gsl/
  brew install gsl

• OpenCV
  http://opencv.org/

brew install opencv```

* Graphviz  
http://www.graphviz.org/  
```brew install graphviz```

* Gnuplot  
http://www.gnuplot.info/  
```brew install gnuplot```


Heroku buildpacks
---

* GSL and Ruby buildpack  
https://github.com/tomwolfe/heroku-buildpack-gsl-ruby

* OpenCV and Ruby buildpack  
https://github.com/lilibethdlc/heroku-buildpack-ruby-opencv