title: acf() function "lag.max" parameter explanation
body: <p>I am using the <code>acf</code> function in Time Series Analysis and have confusion understanding the <code>lag.max</code> argument in it.</p>
  
  <p>The help for the function gives the following explanation for <code>lag.max</code>-</p>
  
  <blockquote>
    <p>lag.max: maximum lag at which to calculate the acf.  Default is
              10*log10(N/m) where N is the number of observations and m the
              number of series.  Will be automatically limited to one less
              than the number of observations in the series.</p>
  </blockquote>
  
  <p>What's <code>m</code> or the number of series?</p>
  
  <p>Say I have a time series having monthyl data for the past 34 months and I need to make a prediction for the next month (or the 35th month).</p>
  
  <p>In this case <code>N</code> will be 34, but what should be <code>m</code> so that I can calculate "lag.max" parameter?</p>
  
  <p>Thanks!</p>