<?xml version="1.0"?> 
<param xml:id='expression_function'> 
  <time_resolution>60</time_resolution> 
  <get> 
    <amdaParam name="density" /> 
    <amdaParam name="speed" /> 
  </get> 
  <process description="sin(density)*cos(speed)+sqrt(density)">sin($density) * cos($speed) + sqrt($density)</process> 
  <output/> 
</param>