public void SecondDerivative2()
{
var derivative = DifferentialCalculus.SecondDerivative(x => 3 * x[0] * x[0] * x[0] + x[1] * x[0] * x[0], 0, 1, 2);
Assert.IsTrue(derivative == 22);
}
public void SecondDerivative()
{
var derivative = DifferentialCalculus.SecondDerivative(x => 3 * x * x * x, 2);
Assert.IsTrue(derivative == 36);
}