<!--
var m = new Array();
var nr=0;
var dir="images/";

var i=0;
m[i]=dir+"illustrationorbit1-s.gif"; i++;
m[i]=dir+"illustrationorbit2-s.gif"; i++;
m[i]=dir+"longorbit-s.gif"; i++;
m[i]=dir+"manyorbits-s.gif"; i++;

var opacity=0;
var increment=3;
var timeout=20;

function setOpacity(obj, opacity) {
  opacity = (opacity == 100)?99.999:opacity;
  obj.style.filter = "alpha(opacity:"+opacity+")";    // IE/Win
  obj.style.KHTMLOpacity = opacity/100;               // Safari<1.2, Konqueror
  obj.style.MozOpacity = opacity/100;                 // Older Mozilla and Firefox
  obj.style.opacity = opacity/100;                    // Safari 1.2, newer Firefox and Mozilla, CSS3
}


function start() {
  if (opacity*(100-opacity)>0) {
     opacity +=increment;
  } else {
     if (opacity<3) {
       nr++;
       if (nr>m.length-1) { nr=0; }
       document.mathdisplay.src=m[nr];
     }
     increment=-increment;
     opacity +=increment;
  }
  timeout=Math.floor(opacity/4);
  if (opacity>95) {timeout=2200;}
  if (opacity<5) {timeout=500;}
  setOpacity(document.mathdisplay,opacity);
  setTimeout("start()",timeout);
}

function run() {
  opacity=100;
  setOpacity(document.mathdisplay,opacity); 
  document.mathdisplay.style.visibility = "visible";
  setTimeout("start()",0);
}

window.onload = function() {run()}
// -->