jquery animation

HTML

<div class="image-wrap">
    <img class="image" src="http://www.vistaar.com/wp-content/uploads/2011/05/dell-logo-100X100.gif">
</div>

CSS

body {
   margin: 0;
   height: 100%;
}
.image-wrap {
    height: 100%;
    position: absolute;
    width: 100%;
}

.image {
    display: block;
    height: 100%;
    left: 0;
    max-height: 100px;
    max-width: 100px;
    position: fixed;
    top: 0;
    width: 100%;
}

JavaScript

$(document).ready(function(){
    animateDiv();
    
});

function makeNewPosition(){
    
    // Get viewport dimensions (remove the dimension of the div)
    var h = $(window).height() - 50;
    var w = $(window).width() - 50;
    
    var nh = Math.floor(Math.random() * h);
    var nw = Math.floor(Math.random() * w);
    
    return [nh,nw];    
    
}

function animateDiv(){
    var newq = makeNewPosition();
    var oldq = $('.image').offset();
    var speed = calcSpeed([oldq.top, oldq.left], newq);
    
    $('.image').animate({ top: newq[0], left: newq[1] }, speed, function(){
      animateDiv();        
    });
    
};

function calcSpeed(prev, next) {
    
    var x = Math.abs(prev[1] - next[1]);
    var y = Math.abs(prev[0] - next[0]);
    
    var greatest = x > y ? x : y;
    
    var speedModifier = 0.1;

    var speed = Math.ceil(greatest/speedModifier);

    return speed;

}