public void TestDifferentiate()
{
MathFunction f = Math.Exp;
MathFunction Df = Math.Exp;
Assert.Equal(Df(-5), NumericalTools.Differentiate(f)(-5), 2);
Assert.Equal(Df(-1), NumericalTools.Differentiate(f)(-1), 2);
Assert.Equal(Df(0), NumericalTools.Differentiate(f)(0), 2);
Assert.Equal(Df(1), NumericalTools.Differentiate(f)(1), 2);
Assert.Equal(Df(5), NumericalTools.Differentiate(f)(5), 2);
f = Math.Sin;
Df = Math.Cos;
Assert.Equal(Df(-5), NumericalTools.Differentiate(f)(-5), 2);
Assert.Equal(Df(-1), NumericalTools.Differentiate(f)(-1), 2);
Assert.Equal(Df(0), NumericalTools.Differentiate(f)(0), 2);
Assert.Equal(Df(1), NumericalTools.Differentiate(f)(1), 2);
Assert.Equal(Df(5), NumericalTools.Differentiate(f)(5), 2);
f = x => Math.Pow(x, 3);
Df = x => 3 * Math.Pow(x, 2);
Assert.Equal(Df(-5), NumericalTools.Differentiate(f)(-5), 2);
Assert.Equal(Df(-1), NumericalTools.Differentiate(f)(-1), 2);
Assert.Equal(Df(0), NumericalTools.Differentiate(f)(0), 2);
Assert.Equal(Df(1), NumericalTools.Differentiate(f)(1), 2);
Assert.Equal(Df(5), NumericalTools.Differentiate(f)(5), 2);
}
