Call JavaScript function inside SVG from Surrounding HTML

I've created a little page just as this one here:

<!DOCTYPE html>
<html>
  <head>
     <title>Test</title>
     <script type="text/javascript">
     function test() {
        executeAnimation();
     }   
     </script>
  </head>
  <body>
     <h1>Tester</h1>
     <embed src="test.svg" type="image/svg+xml" /> 
     <hr />
     <input type='button' value='Test' onclick='test()' />
  </body>
</html>

The test.svg looks like this:

<?xml version="1.0" ?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20010904//EN"
 "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
<svg id="testSvgId" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="950" height="900">
     <title>Title</title>
     <desc>Desc</desc>
     <defs>
          <script type="text/javascript">
          <![CDATA[
          function executeAnimation () {
              document.getElementById('anim').beginElement();
          }
          ]]>
          </script>
     </defs>
     <ellipse cx="500" cy="1090" rx="600" ry="0" fill="rgb(94,114,54)">
          <animate id="anim" attributeType="XML" attributeName="ry" begin="indefinite" dur="2s" from="0" to="350" fill="freeze" />
     </ellipse>
</svg>

As you can see, I want to call from JavaScript in the HTML page the function executeAnimation() which is defined insite the SVG image. This actually does not work.

I also tried this:

<svg onload='onloadFunction()'...>
...
function onloadFunction() {
    alert('i am loading');
    window.executeAnimation = executeAnimation();
}

This was suggested in another forum, but this did also not work (window.executeAnimation was undefined from outside).

What would be the real correct way to do this?