/// @throws IllegalArgumentException
/// @throws NoConvergenceException
static FinanceCalcResult <double> Besselk1(double fNum)
{
double fRet;
if (fNum <= 2.0)
{
double fNum2 = fNum * 0.5;
double y = fNum2 * fNum2;
var iResult = new BesselIimpl().BesselI(fNum, 1);
if (iResult.HasError)
{
return(iResult);
}
fRet = Math.Log(fNum2) * iResult.Result +
(1.0 + y * (0.15443144 + y * (-0.67278579 + y * (-0.18156897 + y * (-0.1919402e-1 +
y * (-0.110404e-2 + y * -0.4686e-4))))))
/ fNum;
}
else
{
double y = 2.0 / fNum;
fRet = Math.Exp(-fNum) / Math.Sqrt(fNum) * (1.25331414 + y * (0.23498619 +
y * (-0.3655620e-1 + y * (0.1504268e-1 + y * (-0.780353e-2 +
y * (0.325614e-2 + y * -0.68245e-3))))));
}
return(new FinanceCalcResult <double>(fRet));
}
static FinanceCalcResult <double> Besselk0(double fNum)
{
double fRet;
if (fNum <= 2.0)
{
double fNum2 = fNum * 0.5;
double y = fNum2 * fNum2;
var iResult = new BesselIimpl().BesselI(fNum, 0);
if (iResult.HasError)
{
return(iResult);
}
fRet = -Math.Log(fNum2) * iResult.Result +
(-0.57721566 + y * (0.42278420 + y * (0.23069756 + y * (0.3488590e-1 +
y * (0.262698e-2 + y * (0.10750e-3 + y * 0.74e-5))))));
}
else
{
double y = 2.0 / fNum;
fRet = Math.Exp(-fNum) / Math.Sqrt(fNum) * (1.25331414 + y * (-0.7832358e-1 +
y * (0.2189568e-1 + y * (-0.1062446e-1 + y * (0.587872e-2 +
y * (-0.251540e-2 + y * 0.53208e-3))))));
}
return(new FinanceCalcResult <double>(fRet));
}
