title: Complex number in R
body: <p>I know that you can easily define a complex number z by doing for instance :
  <code>z &lt;- 3 + 2i</code>. But when I want to define a function that creates a complex number:</p>
  
  <pre><code>f &lt;- function(x,y){
  x + yi
  }
  f(1,2)
  </code></pre>
  
  <p>I get this error message :</p>
  
  <blockquote>
    <p>Error in f(1, 2) : object 'yi' not found.</p>
  </blockquote>
  
  <p>I don't want to use the <code>complex</code> function, because in my case, it is really difficult to find the real and imaginary parts of my complex number.</p>
  
  <p>How can I do ?</p>