function doBackScroll() {
var pos = getScrollPosition();
while (pos.x + pos.y > 0){

var pitch = Math.min(Math.floor(600 * Math.pow(pos.y,-0.4)),50);
pos.x = Math.floor(pos.x / 2);
pos.y = Math.floor(pos.y - (pos.y / pitch));
window.scrollTo(pos.x,pos.y );
}
}
function getScrollPosition() {
var obj = new Object();
var agt=navigator.userAgent.toLowerCase();
var is_ie = (agt.indexOf("msie") != -1);
obj.x = (is_ie) ? (document.body.scrollLeft || document.documentElement.scrollLeft) : window.pageXOffset;
obj.y = (is_ie) ? (document.body.scrollTop || document.documentElement.scrollTop) : window.pageYOffset;
return obj;
}

function addListener(elem, eventType, funcRef, capture) {
    if(!elem) { return false; }

    if(elem.addEventListener) {
        elem.addEventListener(eventType, funcRef, capture);
    } else if(elem.attachEvent) {
        elem.attachEvent('on' + eventType, funcRef);
    } else {
        return false;
    }
    return true;
}
function addLoadListener(e) {
    addListener(document.getElementById('toPageTop'), 'click', doBackScroll, false);

for(var i=0;i<document.getElementsByTagName('*').length;i++){
if(document.getElementsByTagName('*')[i].className == 'toPageTop'){
    addListener(document.getElementsByTagName('*')[i], 'click', doBackScroll, false);
}
}


}
addListener(window, 'load', addLoadListener, false);