title: Why are the arguments to atan2 Y,X rather than X,Y?
body: <p>In C the atan2 function has the following signature:</p>
  
  <pre><code>double atan2( double y, double x );
  </code></pre>
  
  <p>Other languages do this as well. This is the only function I know of that takes its arguments in Y,X order rather than X,Y order, and it screws me up regularly because when I think coordinates, I think (X,Y).</p>
  
  <p>Does anyone know why atan2's argument order convention is this way?</p>