/// <summary>
/// B-Spline Kernel Function
/// </summary>
///
/// <param name="x">Vector <c>x</c> in input space.</param>
/// <param name="y">Vector <c>y</c> in input space.</param>
/// <returns>Dot product in feature (kernel) space.</returns>
///
public override double Function(double[] x, double[] y)
{
double k = 1.0;
int n = 2 * order + 1;
for (int p = 0; p < x.Length; p++)
{
k *= Special.BSpline(n, x[p] - y[p]);
}
return(k);
}
public void FunctionTest()
{
{
double expected = cubic(0.5);
double actual = Special.BSpline(3, 0.5);
Assert.AreEqual(0.47916666666666669, actual, 1e-8);
Assert.AreEqual(expected, actual, 1e-8);
}
for (double x = -10; x < 10; x = Math.Round(x + 0.01, 2))
{
double expected = cubic(x);
double actual = Special.BSpline(3, x);
Assert.IsTrue(expected.IsEqual(actual, rtol: 1e-5));
}
}