title: Double integral in MATLAB
body: <p>I'm trying to find the power in an aperture from a Gaussian beam, where the aperture is offset from the beam center. The solution is the following equation (<a href="http://www.opticsinfobase.org/abstract.cfm?URI=jlt-25-7-1702" rel="nofollow noreferrer">reference</a>) (sorry, no LaTeX here):</p>
  
  <p><img src="https://i.stack.imgur.com/TM50h.png" alt="enter image description here"></p>
  
  <p><em>Wz</em> is a constant, along with <em>a</em> and <em>r</em>. I'm not sure how I can do something like this with MATLAB. Does anyone have a suggestion? I know there's a <code>dblquad()</code> function, but it assumes that the limits of integration are fixed, and not dependent on each other.</p>