title: In R, what is the difference between class ts and class timeSeries?
body: <p>In R, what is the difference between class <code>ts</code> and class <code>timeSeries</code>? I think I am getting a problem in <code>HoltWinters</code> because of that. I'm getting:</p>
  
  <pre><code>data(LakeHuron)
  x &lt;- LakeHuron
  before &lt;- window(x, end=1935)
  after &lt;- window(x, start=1935)
  a &lt;- .2
  b &lt;- 0
  g &lt;- 0
  model &lt;- HoltWinters(before, alpha=a, beta=b, gamma=g)
  </code></pre>
  
  <blockquote>
    <p>"Error in decompose(ts(x[1L:wind], start = start(x), frequency = f), seasonal) : 
      time series has no or less than 2 periods"</p>
  </blockquote>
  
  <p>even though <code>gamma=0</code>.</p>
  
  <p>Running R 2.11.1 (win32 x86) on a Windows 7 x64 machine.</p>