var t = 0;

function fade(){
    testi();
}

function testi(){
        var interval = 7000;
        opacity(t);
        setTimeout("testi()", interval);
        if(t >= (testi_lenght-1)){
            t = 0;
        }else{
            t++;
        }
}
function opacity(id) {

        if(id != 0){
            var old_id = id-1;
        }else{
            old_id = (testi_lenght-1);
        }
            var old_div = "test_div_" + old_id ;
            var old_testi_div = document.getElementById(old_div).style;
            old_testi_div.visibility = "hidden";

	var new_id = "test_div_" + id ;
        //alert(new_id);
        var new_testi_div = document.getElementById(new_id).style;

        new_testi_div.visibility = "visible";

	//alert(new_id);
	var opacStart = 0;
	var opacEnd = 100;
	//speed for each frame
	var speed = Math.round(400 / 100);
	var timer = 0;

		for(i = opacStart; i <= opacEnd; i++){
			setTimeout("changeOpac(" + i + ", '" + new_id + "')", (timer * speed));
			timer++;
		}
}
function changeOpac(opacity, id) {
	var new_id = id;
	var object = document.getElementById(new_id).style;
	object.opacity = (opacity / 100);
	object.MozOpacity = (opacity / 100);
	object.KhtmlOpacity = (opacity / 100);
	object.filter = "alpha(opacity=" + opacity + ")";
}