title: How to define a function with varying amount parameters?
body: <p>I am new to <code>proc fcmp</code> and I want to know how to write a user-defined function with varying amount parameters, which like <code>whichc()</code> or   <code>coalesce()</code>, in SAS.</p>
  
  <p>I will be grateful if anybody could give me some hints.</p>