myPix = new Array("img/img_01.gif",
                  "img/img_02.gif",
                  "img/img_03.gif",
                  "img/img_04.gif",
                  "img/img_05.gif",
                  "img/img_06.gif",
                  "img/img_07.gif",
                  "img/img_08.gif",
                  "img/img_09.gif",
                  "img/img_10.gif",
                  "img/img_11.gif",
                  "img/img_12.gif",
                  "img/img_13.gif",
                  "img/img_14.gif",
                  "img/img_15.gif")

imgCt = myPix.length

function choosePic() {
	if (document.images) {
		randomNum = Math.floor((Math.random() * imgCt))
		document.myPicture.src=myPix[randomNum]
	}
}