how to do clustering of markers on google map -

well trying clustering of markers on google map. have found example http://google-maps-utility-library-v3.googlecode.com/svn/tags/markerclusterer/1.0/examples/simple_example.html not able understand use of following code in it-

<script type="text/javascript">   var script = '<script type="text/javascript" src="../src/markerclusterer';   if (document.location.search.indexof('packed') !== -1) {     script += '_packed';   }   if (document.location.search.indexof('compiled') !== -1) {     script += '_compiled';   }   script += '.js"><' + '/script>';   document.write(script); </script> 

what full src used there. when copy code , use on laptop not working. please explain why? , best ways clustering of markers on google map.

<script type="text/javascript">   var script = '<script type="text/javascript" src="../src/markerclusterer';   if (document.location.search.indexof('packed') !== -1) {     script += '_packed'; 

if url of page contains string 'packed', includes script @ "../src/markercluseter_packed.js"

  }   if (document.location.search.indexof('compiled') !== -1) {     script += '_compiled'; 

if url of page contains string 'compiled', includes script @ "../src/markercluseter_compiled.js"

  }   script += '.js"><' + '/script>';   document.write(script); 

oherwise includes script @ "../src/markerclusterer.js"

</script> 

do of files exist in ../src/ directory relative page on laptop?