public void TestSine()
        {
            //Arrange
            VariableNode variableNode = new VariableNode();
            PiNode       piNode       = new PiNode();
            SineFunction sineNode1    = new SineFunction(variableNode);
            SineFunction sineNode2    = new SineFunction(piNode);

            //Act
            double result1 = sineNode1.Calculate(0);
            double result2 = sineNode2.Calculate(0);

            //Assert
            Assert.AreEqual(0, result1);
            Assert.AreEqual(0, Math.Round(result2, 15));
        }
        public void TestCosine()
        {
            //Arrange
            VariableNode   variableNode = new VariableNode();
            PiNode         piNode       = new PiNode();
            CosineFunction cosineNode1  = new CosineFunction(variableNode);
            CosineFunction cosineNode2  = new CosineFunction(piNode);

            //Act
            double result1 = cosineNode1.Calculate(0);
            double result2 = cosineNode2.Calculate(0);

            //Assert
            Assert.AreEqual(1, result1);
            Assert.AreEqual(-1, result2);
        }