public void ToXml(string xmlFile)
    {
        //Dictionary used: Values
        XDocument doc = new XDocument(
            new XDeclaration("1.0", "utf-8", null));
        XElement xRoot = new XElement("RootElement");
        doc.Add(xRoot);
        Dictionary<double, double[]>.KeyCollection keys = Values.Keys;

        foreach(double key in keys)
        {
            XElement inner = new XElement("InnerElement",
                new XAttribute("value", key),
                new XElement("TestValue1", Values[key][0]),
                new XElement("Testvalue2", Values[key][1]),
                new XElement("TestValue3", Values[key][2]),
                new XElement("TestValue4", Values[key][3]),
                new XElement("TestValue5", Values[key][4]),
                new XElement("TestValue6", Values[key][5]));

            xRoot.Add(inner);
        }
        doc.Save(xmlFile);
    }