function EW_checknumber(object_value) {
	if (object_value.length == 0)
		return true;
	
	var start_format = " .+-0123456789";
	var number_format = " .0123456789";
	var check_char;
	var decimal = false;
	var trailing_blank = false;
	var digits = false;
	
	check_char = start_format.indexOf(object_value.charAt(0));
	if (check_char == 1)
		decimal = true;
	else if (check_char < 1)
		return false;
	 
	for (var i = 1; i < object_value.length; i++)	{
		check_char = number_format.indexOf(object_value.charAt(i))
		if (check_char < 0) {
			return false;
		} else if (check_char == 1)	{
			if (decimal)
				return false;
			else
				decimal = true;
		} else if (check_char == 0) {
			if (decimal || digits)	
			trailing_blank = true;
		}	else if (trailing_blank) { 
			return false;
		} else {
			digits = true;
		}
	}	
	
	return true;
}

function EW_checkinteger(object_value) {
	if (object_value.length == 0)
		return true;
	
	var decimal_format = ".";
	var check_char;
	
	check_char = object_value.indexOf(decimal_format);
	if (check_char < 1)
		return EW_checknumber(object_value);
	else
		return false;
}

function IsNumeric(aField)
{
	if ( aField.value != "" )	{
		for( var i=0; i<=aField.value.length-1; i++ ) {
			if ( ( aField.value.charAt( i ) < '0' ) || ( aField.value.charAt( i ) > '9' ) )	{
				alert( "Η τιμή που δώσατε δεν είναι αριθμητική!" );
				aField.focus();
				return false;
			}
		}
	}
	return true;
}