void TestDerivative(Expression <Func <double, double> > function)
{
var f = function.Compile();
double eps = 1e-7;
var dfunction = Algebra.Differentiate(function);
var df = dfunction.Compile();
for (double x = 0; x < 5; x += 0.1)
{
Assert.AreEqual(df(x), (f(x + eps) - f(x)) / eps, 1e-5, $"Error on function {function.Body}");
}
}
public void InformativeMessage_OnUnknownFunction()
{
var ex = Assert.Throws <ArgumentException>(() => Algebra.Differentiate(z => Math.Max(z, 2 * z)));
Assert.That(ex.Message, Does.Contain("Max"));
}
public void InformativeMessage_OnNotSupportedSyntax()
{
var ex = Assert.Throws <ArgumentException>(() => Algebra.Differentiate(z => z.ToString().Length));
Assert.That(ex.Message, Does.Contain("ToString"));
}
