function valid_email(email)
{
    var mask = /^[a-zA-Z0-9_\.\-]+@([a-zA-Z0-9][a-zA-Z0-9-]+\.)+[a-zA-Z]{2,6}$/;
    return mask.test(email);
}

function validate_email(email)
{
	if (!valid_email(email))
	{
		alert ("Email address is invalid");
		return false;
	}
	return true;
}

function valid_number(num)
{
    var mask = /^[0-9,]+$/;
	return mask.test(num);
}

function validate_numbers(id1, id2)
{
	num1 = document.getElementById(id1).value;
	if (!valid_number(num1))
	{
		alert ("Value is invalid");
		return false;
	}
	if (id2)
	{
		num2 = document.getElementById(id2).value;
		if (!valid_number(num2))
		{
			alert ("Value is invalid");
			return false;
		}
	}
	return true;
}

function validate_contact()
{
	error_msg = "";	
	if (!document.getElementById('id_name').value)
		error_msg += "Please enter your name.\n";
	email = document.getElementById('id_email').value;
	if (!email)
		error_msg += "Please enter email address.\n";
	else
	{
		if (!valid_email(email))
			error_msg += "Please enter valid email address.\n";
	}
	if (!document.getElementById('id_question').value)
		error_msg += "Please enter your question.";
	if (error_msg)
	{
		alert(error_msg);
		return false;
	}
	return true;
}