function load_map() {

   var marker = false;

   var map_canvas = document.getElementById("map_canvas")

   // get options
   var center_lat = document.getElementById('center_lat');
   var center_lng = document.getElementById('center_lng');
   var zoom       = document.getElementById('zoom');
   var marker_lat = document.getElementById('marker_lat');
   var marker_lng = document.getElementById('marker_lng');

   // center of map
   var centerLatLng = new google.maps.LatLng(center_lat.value, center_lng.value);
   
   // set map otions
   var mapOptions = {
      zoom: parseInt(zoom.value),
      center: centerLatLng,
      scrollwheel: false,
      mapTypeId: google.maps.MapTypeId.ROADMAP
   }
   
   // create map
   var map = new google.maps.Map(map_canvas, mapOptions);

   
   // set marker
   if (marker_lat && marker_lng && marker_lat.value!='' && marker_lng.value!='' ) {
      var markerLatLng = new google.maps.LatLng(parseFloat(marker_lat.value), parseFloat(marker_lng.value));        
      marker = create_marker(map,markerLatLng);
   }
            
}

function create_marker(map,markerLatLng) {

   var marker = new google.maps.Marker({
      position: markerLatLng,
      draggable : false, 
      map: map
   });   

   return marker;

}