function isDigits(input) {
// input must contain digits only
	var pattern = /^\d+$/
	return pattern.test(input);
}

function isDecimal(input) {
// input must contain leading digits and may contain a decimal and digits after
	var pattern = /^\d+(\.\d+)?$/
	return pattern.test(input);
}

function isValidEmail(email) {
// taken from The Javascript Anthology, www.sitepoint.com
	var pattern = /^[\w\.\-]+@([\w\-]+\.)+[a-zA-Z]+$/;
	return pattern.test(email);
}