private static double PwdRinLaplaceSpace(double s, double cd, double skinFactor)
{
var rz = Math.Sqrt(s);
var p1 = SpecialFunctions.BesselK0(rz) + skinFactor * rz * SpecialFunctions.BesselK1(rz);
var p2 = s * (rz * SpecialFunctions.BesselK1(rz) + cd * s * p1);
return(p1 / p2);
}
public void BesselK0Exact(double x, double expected)
{
AssertHelpers.AlmostEqualRelative(expected, SpecialFunctions.BesselK0(x), 14);
}
public void BesselK0Approx([Range(0.20, 2.0, 0.20)] double x)
{
// Approx by Abramowitz/Stegun 9.8.5
Assert.AreEqual(Evaluate.Polynomial(x / 2.0, -Math.Log(x / 2.0) * SpecialFunctions.BesselI0(x) - 0.57721566, 0.0, 0.42278420, 0.0, 0.23069756, 0.0, 0.03488590, 0.0, 0.00262698, 0.0, 0.00010750, 0.0, 0.00000740), SpecialFunctions.BesselK0(x), 1e-8);
}