public void DerivativeTest()
{
double[] expected =
{
0.31831, 0.315158, 0.306067, 0.292027, 0.274405, 0.254648,
0.234051, 0.213631, 0.194091, 0.175862, 0.159155
};
CauchitLinkFunction target = new CauchitLinkFunction();
for (int i = 0; i < 11; i++)
{
double x = i / 10.0;
double y = target.Inverse(x);
double d1 = target.Derivative(x);
double d2 = target.Derivative2(y);
Assert.AreEqual(expected[i], d1, 1e-6);
Assert.AreEqual(expected[i], d2, 1e-6);
Assert.IsFalse(Double.IsNaN(d1));
Assert.IsFalse(Double.IsNaN(d2));
}
}
public void CauchitLinkFunctionConstructorTest()
{
CauchitLinkFunction target = new CauchitLinkFunction();
Assert.AreEqual(0.5, target.A);
Assert.AreEqual(1 / Math.PI, target.B);
for (int i = 0; i < 11; i++)
{
double x = i / 10.0;
double y = Math.Tan(Math.PI * (x - 0.5));
Assert.AreEqual(y, target.Function(x), 1e-10);
Assert.AreEqual(x, target.Inverse(y), 1e-10);
}
}
