// globals are bad
var someGlobalStop = false;

function createAnimateFunction(randMax, moveMin, duration) {
  var __animate = function (){
        var rnd = Math.ceil(Math.random() * randMax) + moveMin,
          rnd2 = Math.ceil(Math.random() * randMax) + moveMin,
          props = {
          marginBottom: rnd,
          marginTop: rnd,
          marginLeft:rnd2,
          marginRight: rnd2
        };
                if(! someGlobalStop)  {
            $(this).animate(props, duration, __animate);
                }
    };

    return __animate;
}

function animatesmall(){
  $('ul.work li.small').each(createAnimateFunction(30, 10, 900));
}
function animatemedium(){
    $('ul.work li.medium').each(createAnimateFunction(50, 20, 1900));
}
function animatelarge(){
    $('ul.work li.large').each(createAnimateFunction(50, 30, 2300));
}