title: Matrix.rb no such file Ruby 1.9.2
body: <p>I have ruby 1.9.2 installed:</p>
  
  <pre><code>alykhan@helium:~$ ruby -v
  ruby 1.9.2p0 (2010-08-18 revision 29036) [x86_64-linux]
  </code></pre>
  
  <p>But in irb when I try to <code>require 'Matrix'</code> I get an error as shown below:</p>
  
  <pre><code>alykhan@helium:~$ irb
  irb(main):001:0&gt; require 'Matrix'
  LoadError: no such file to load -- Matrix
      from &lt;internal:lib/rubygems/custom_require&gt;:29:in `require'
      from &lt;internal:lib/rubygems/custom_require&gt;:29:in `require'
      from (irb):1
      from /usr/local/ruby/bin/irb:12:in `&lt;main&gt;'
  irb(main):002:0&gt;
  </code></pre>
  
  <p>Do i need to install a specific gem to get the Matrix lib?</p>