The linalg dependency is a bit of a nightmare for anyone running a modern gcc (4 vs 3) from what I can see. This could be avoided by supporting/using http://rb-gsl.rubyforge.org/ the ruby bindings to the gnu scientific libs.

In order to use I seem to need to :

require 'rubygems'
require 'semantic'

Shouldn't that be :

require 'rsemantic'

for consistency ?

In order to get the gem to work I have to :

  require 'rubygems'
  require '/usr/lib/ruby/gems/1.8/gems/josephwilk-rsemantic-0.1.3/lib/semantic'

rather than :

require 'rubygems'
require 'semantic'

This just gives :

 ./semantic.rb:14: uninitialized constant Semantic (NameError)

When running :

 D1 = "The cat in the hat disabled"
 D2 = "A cat is a fine pet ponies." 
 D3 = "Dogs and cats make good pets"
 D4 = "I haven't got a hat."
 #verbose mode so it shows us all the different stages
 search = Semantic::Search.new([D1, D2, D3, D4], :verbose => true)

Not sure if this is a bug or not, although it seems a little strange.

Running the example at : http://wiki.github.com/josephwilk/rsemantic

But changing the docs to :

documents = ["The cat in the hat disabled",
             "A cat is a fine pet ponies.",
             "Do and cats make good pets.",
             "I haven't got a cat."]

Returns :

1.0
0.0
0.0
NaN

0.0
0.0
0.0
NaN