var img_name = new Array("../images/subpic_1.gif",
"../images/subpic_2.gif",
"../images/subpic_3.gif",
"../images/subpic_4.gif",
"../images/subpic_5.gif",
"../images/subpic_6.gif",
"../images/subpic_7.gif",
"../images/subpic_8.gif",
"../images/subpic_12.gif");


var l = img_name.length;

var rnd_no = Math.round((l-1)*Math.random());

document.subpic.src = img_name[rnd_no];