public void DiffPowConstant()
{
Expression <Del1> expression = (x) => Math.Pow(x, 3);
Assert.AreEqual(
new ScalarProduct <double>(new Constant <double>(3.0), new Pow <double>(VariableNode.Make <double>(0, "x"), new Constant <double>(2.0))).ToString(),
ComputerAlgebra.Differentiate(Expressions2Tree.Parse(expression.Body), variable: "x").ToString());
}
public void DiffProduct()
{
Expression <Del2> expression = (x, y) => x * y;
Assert.AreEqual(
"y",
ComputerAlgebra.Differentiate(expression.Body, variable: "x").ToString());
}
public void DiffNegate()
{
Expression <Del1> expression = (x) => - x;
Assert.AreEqual(
"-1",
ComputerAlgebra.Differentiate(expression.Body, variable: "x").ToString());
}
public void DiffDivide()
{
Expression <Del2> expression = (x, y) => x / y;
Assert.AreEqual(
new Divide <double>(
VariableNode.Make <double>(1, "y"),
new Pow <double>(VariableNode.Make <double>(1, "y"), new Constant <double>(2))).ToString(),
ComputerAlgebra.Differentiate(Expressions2Tree.Parse(expression.Body), variable: "x").ToString());
}
public void DiffPowY()
{
Expression <Del2> expression = (x, y) => Math.Pow(x, y);
Assert.AreEqual(
new ScalarProduct <double>(
new Pow <double>(
VariableNode.Make <double>(0, "x"),
VariableNode.Make <double>(1, "y")),
new Ln(VariableNode.Make <double>(0, "x")))
.ToString(),
ComputerAlgebra.Differentiate(Expressions2Tree.Parse(expression.Body), variable: "y").ToString());
}
static void Main()
{
//Type the function you want to differentiate
Expression <Func <double, double, double, double> > function = (x, y, z) => Math.Pow(x, 3) * y - Math.Pow(x, y) + 5 * z;
var node = Expressions2Tree.Parse(function);
// Differentiation
var resultFromDiffX = ComputerAlgebra.Differentiate(node, variable: "x");
var resultFromDiffY = ComputerAlgebra.Differentiate(node, variable: "y");
var resultFromDiffZ = ComputerAlgebra.Differentiate(node, variable: "z");
// Output
Console.WriteLine("Initial function:{1}F(x,y,z) = {0}{1}", node, Environment.NewLine);
Console.WriteLine("dF/dx = {0}{1}", resultFromDiffX, Environment.NewLine);
Console.WriteLine("dF/dy = {0}{1}", resultFromDiffY, Environment.NewLine);
Console.WriteLine("dF/dz = {0}{1}", resultFromDiffZ, Environment.NewLine);
}