public void TestFindRoot()
{
var func = new Func <double, double>(x => 5 * Math.Pow(x, 3) + 2 * Math.Pow(x, 2) + 4 * x + 1);
var result = Dsp.FindRoot(func, 0, 1);
var target = -0.261840345691399;
Assert.AreEqual(result, target, 1e-14);
var func2 = new Func <double, double>(x => Math.Pow(x, 2) + 2);
Assert.Throws <Exception>(() => Dsp.FindRoot(func2, 0, 1));
Assert.Throws <ArgumentNullException>(() => Dsp.FindRoot(null, 0, 1));
Assert.Throws <ArgumentOutOfRangeException>(() => Dsp.FindRoot(func, 0, 0));
Assert.Throws <ArgumentOutOfRangeException>(() => Dsp.FindRoot(func, 0, 1, -1));
}