function intval(v) {

    v = parseInt(v);

    return isNaN(v) ? 0 : v;

}

function getPos(e) {

    var l = 0;

    var t = 0;

    var w = intval(e.style.width);

    var h = intval(e.style.height);

    var wb = e.offsetWidth;

    var hb = e.offsetHeight;

    while (e.offsetParent) {

        l += e.offsetLeft + (e.currentStyle ? intval(e.currentStyle.borderLeftWidth) : 0);

        t += e.offsetTop + (e.currentStyle ? intval(e.currentStyle.borderTopWidth) : 0);

        e = e.offsetParent;

    }

    l += e.offsetLeft + (e.currentStyle ? intval(e.currentStyle.borderLeftWidth) : 0);

    t += e.offsetTop + (e.currentStyle ? intval(e.currentStyle.borderTopWidth) : 0);

    return {

        x: l,

        y: t,

        w: w,

        h: h,

        wb: wb,

        hb: hb

    };

}

function getScroll() {

    var t, l, w, h;

    if (document.documentElement && document.documentElement.scrollTop) {

        t = document.documentElement.scrollTop;

        l = document.documentElement.scrollLeft;

        w = document.documentElement.scrollWidth;

        h = document.documentElement.scrollHeight;

    } else if (document.body) {

        t = document.body.scrollTop;

        l = document.body.scrollLeft;

        w = document.body.scrollWidth;

        h = document.body.scrollHeight;

    }

    return {

        t: t,

        l: l,

        w: w,

        h: h

    };

}

function scroller(el, duration) {

    if (typeof el != "object") {

        el = document.getElementById(el);

    }

    if (!el) return;

    var z = this;

    z.el = el;

    z.p = getPos(el);

    z.s = getScroll();

    z.clear = function() {

        window.clearInterval(z.timer);

        z.timer = null

    };

    z.t = (new Date).getTime();

    z.step = function() {

        var t = (new Date).getTime();

        var p = (t - z.t) / duration;

        if (t >= duration + z.t) {

            z.clear();

            window.setTimeout(function() {

                z.scroll(z.p.y, z.p.x)

            }, 13);

        } else {

            st = ((-Math.cos(p * Math.PI) / 2) + 0.5) * (z.p.y - z.s.t) + z.s.t;

            sl = ((-Math.cos(p * Math.PI) / 2) + 0.5) * (z.p.x - z.s.l) + z.s.l;

            z.scroll(st, sl);

        }

    };

    z.scroll = function(t, l) {

        window.scrollTo(l, t)

    };

    z.timer = window.setInterval(function() {

        z.step();

    }, 13);

}

onclick="scroller('igbook', 200)"