title: SAS--how to calculate return from price data?
body: <p>I am using SAS. I have a dataset called EOD_close_rtn, which looks as below:</p>
  
  <pre><code>date        CF888   A9888   AG888   AL888   AU888   C9888   CU888   ER888   IF888   J9888
  4-Jun-13    20220   4828    4621    14855   281.11  2434    53060   2628    2561.4  1489
  5-Jun-13    20210   4827    4620    14850   281.1   2435    53080   2627    2561.6  1489
  6-Jun-13    20215   4829    4621    14860   281.14  2435    53080   2627    2561.4  1491
  </code></pre>
  
  <p>The first column is the date, and the rest columns are prices corresponding to the contract names on top. I want to calculate the daily return for each contract, and the output should be in the same format. I tried to use LAG function, but don't know how to apply the same functions to all columns. </p>