// random image
var iValue, rNumber;

var img1=new Image();
var img2=new Image();
var img3=new Image();
//var img4=new Image();

img1.src="images/main_img1.jpg";
img2.src="images/main_img2.jpg";
img3.src="images/main_img3.jpg";
//img4.src="images/main_img4.jpg";

function displayImage(){
	iValue=Math.random()*3;
//	iValue=Math.random()*4;
	rNumber=Math.ceil(iValue);
	if(rNumber==0) rNumber++;
	document.mainimg.src=eval("img"+rNumber+".src");
}