var rand1 = 0;
var useRand = 0;

images = new Array;
images[1] = new Image();
images[1].src = "./Images/pr1.jpg";
images[2] = new Image();
images[2].src = "./Images/pr2.jpg";
images[3] = new Image();
images[3].src = "./Images/pr3.jpg";
images[4] = new Image();
images[4].src = "./Images/pr4.jpg";
images[5] = new Image();
images[5].src = "./Images/pr5.jpg";
images[6] = new Image();
images[6].src = "./Images/pr6.jpg";
images[7] = new Image();
images[7].src = "./Images/pr7.jpg";
images[8] = new Image();
images[8].src = "./Images/pr8.jpg";
images[9] = new Image();
images[9].src = "./Images/pr9.jpg";
images[10] = new Image();
images[10].src = "./Images/pr10.jpg";
images[11] = new Image();
images[11].src = "./Images/pr11.jpg";
images[12] = new Image();
images[12].src = "./Images/pr12.jpg";
images[13] = new Image();
images[13].src = "./Images/pr13.jpg";

function swapPic() {
var imgnum = images.length - 1;
do {
var randnum = Math.random();
rand1 = Math.round((imgnum - 1) * randnum) + 1;
} while (rand1 == useRand);
useRand = rand1;
document.randimg.src = images[useRand].src;
}