random.m=714025; random.a=4096; random.c=150889;
random.seed = (new Date()).getTime()%random.m;
function random()
{
  random.seed = (random.seed*random.a + random.c) % random.m;
  return random.seed / random.m;
}

function randomizeimages()
{
  randomizeimage('image1', 4, 'gfx/headerphoto/', '.jpg');
}
function randomizeimage(img, count, base, type)
{
  document.images[img].src = base + Math.round(random() * count) + type;
}