public void Test1()
        {
            VectorD state  = new VectorD(new double[] { 0, 1 });
            VectorD result = new RungeKutta4IntegratorD(GetFirstOrderDerivatives).Integrate(state, 2, 2.5);

            Assert.AreEqual(0, result[0]);
            Assert.AreEqual(3.06103515625, result[1]);
        }
        public void Test1()
        {
            VectorD state = new VectorD(new double[]{ 0, 1 });
              VectorD result = new RungeKutta4IntegratorD(GetFirstOrderDerivatives).Integrate(state, 2, 2.5);

              Assert.AreEqual(0, result[0]);
              Assert.AreEqual(3.06103515625, result[1]);
        }