// calculate position of a 2nd-order motion equation
// dist = total distance required to move, time = total time to take
// steep = [0,1] determines motion; value is fraction of dist travelled at .5time
// t = current time step
// x = At^2 + Bt
function discreteQuad(dist,time,steep,t) {
  var A = (2*dist*(1-2*steep))/(time*time);
  var B = (dist/time)*(4*steep-1);
  return(Math.round(A*t*t+B*t));
}

// given element ID, change opacity (=[0,100])
function changeOpacity(elementId,opacity) {
  var mozOpacity=opacity/100;
  var el = document.getElementById(elementId);
  el.style.MozOpacity=mozOpacity;
  if (el.filters) { el.filters.alpha.opacity=opacity; }
}

function internetExplorerBlows() {
  for(var i=0; i<document.images.length; i++) {
    var img = document.images[i];
    var imgName = img.src.toUpperCase();
    if (imgName.substring(imgName.length-3, imgName.length) == "PNG") {
      var imgID = (img.id) ? "id='" + img.id + "' " : "";
      var imgClass = (img.className) ? "class='" + img.className + "' " : "";
      var imgTitle = (img.title) ? "title='" + img.title + "' " : "title='" + img.alt + "' ";
      var imgStyle = "display:inline-block;" + img.style.cssText;		
      var strNewHTML = "<span " + imgID + imgClass + imgTitle + " style=\"" + "width:" 
                       + img.width + "px; height:" + img.height + "px;" + imgStyle + ";"
                       + "filter:progid:DXImageTransform.Microsoft.AlphaImageLoader"
                       + "(src=\'" + img.src + "\', sizingMethod='scale');\"></span>"; 
      img.outerHTML = strNewHTML;
      i = i-1;
    }
  }
}