var maxImage = 4;
var usedImage;


function swapImage() {
	var newImage = randomNum(1,maxImage);
	
	while(newImage == usedImage) {
		newImage = randomNum(1,maxImage);
	};
	
	usedImage = newImage
	document.getElementById('headpic_change').className='headpic_change'+newImage;
};

function randomNum(minVal,maxVal) {
	var floatVal = 0
	var randVal = minVal+(Math.random()*(maxVal-minVal));
	return typeof floatVal=='undefined'?Math.round(randVal):randVal.toFixed(floatVal);
}