title: Calculate difference of numbers in two files
body: <p>Say I have two files where there is one number per line</p>
  
  <pre><code>File 1      file 2
  0.12        0.11     
  0.121       0.454 
  ....        .... 
  </code></pre>
  
  <p>I want to create file or output difference between each number on  to the screen, so that result looks like</p>
  
  <pre><code> 0.0099
  -0.333
   ......
  </code></pre>
  
  <p>You can use bash/awk/sed </p>