title: Does ruby calculate floats wrong?
body: <p>Whats wrong here? (ruby version: 1.9.2p290 (2011-07-09 revision 32553) [x86_64-darwin11.0.0]</p>
  
  <pre><code>x = 523.8
  w = 46.9
  xm = x + w
  assert_equal w, (xm - x) # FAILS with: &lt;46.9&gt; expected but was &lt;46.89999999999998&gt;
  </code></pre>