title: the error happening in the gnuplot
body: <p>When I type the instruction </p>
  
  <pre><code>gnuplot&gt;plot "cbr_delay"
  </code></pre>
  
  <p>in the terminal,the system show error as follows</p>
  
  <pre><code>          0.100000 0.038706
  ^
  "cbr_delay", line 1: invalid command
  </code></pre>
  
  <p>the file cbr_delay is shown </p>
  
  <pre><code>0.100000 0.038706
  0.108000 0.038706
  0.116000 0.038706
  0.124000 0.038706
  0.132000 0.038706
  0.140000 0.038706
  0.148000 0.038706
  0.156000 0.038706
  0.164000 0.038706
  0.172000 0.038706
  0.180000 0.038706
  0.188000 0.038706
  0.196000 0.038706
  0.204000 0.038706
  0.212000 0.038706
  0.220000 0.038706
  0.228000 0.038706
  0.236000 0.038706
  0.244000 0.038706
  0.252000 0.038706
  </code></pre>
  
  <p>what can i do to avoid the error?</p>