title: Using gems via Rubygems in windows - path failure
body: <p>I have installed ruby 1.9.3, with RubyInstaller and DevKit. I installed the required gem I'm looking forward to use, but no matter what I do i can't get it working. I run my program and i get the following runtime erro: </p>
  
  <pre><code>C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/gnuplot-2.6.2/lib/gnuplot.r
  b:59:in `gnuplot': gnuplot executable not found on path (RuntimeError)
          from C:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/gnuplot-2.6.2/
  lib/gnuplot.rb:74:in `open'
          from cluster.rb:182:in `&lt;main&gt;'
  </code></pre>
  
  <p>What have i done wrong? I did try to add <code>require rubygems</code>, run <code>:cmd&gt;&gt; ruby -rubygems ...(params)...</code>, I installed the gem via <code>gem install gem_name</code> in the curent working directorie, but i can't make it find my gems. </p>
  
  <p>PS: I encounter this problem on windows OS.</p>
  
  <p>Solution addition: the path C:....\gnuplot.exe must be added to the PATH variable</p>