// Kahl and Jackel (2005) Heston price, using an integration range of [0,1].
// From "Not-so-Complex Algorithms in the Heston model"
public double HestonPriceKahlJackel(HParam param, OpSet settings, double[] X, double[] W)
{
int N = X.Length;
double kappa = param.kappa;
double theta = param.theta;
double sigma = param.sigma;
double v0 = param.v0;
double rho = param.rho;
double lambda = param.lambda;
double S = settings.S;
double K = settings.K;
double T = settings.T;
double r = settings.r;
double q = settings.q;
string PutCall = settings.PutCall;
// Forward price
double F = S * Math.Exp((r - q) * T);
// Required quantities for integrand
double Cinf = Math.Sqrt(1 - rho * rho) / sigma * (v0 + kappa * theta * T);
// Required quantities for f1
double ImC1 = (Math.Exp((rho * sigma - kappa) * T) * theta * kappa + theta * kappa * ((kappa - rho * sigma) * T - 1.0)) / 2.0 / Math.Pow(kappa - rho * sigma, 2);
double ImD1 = (1.0 - Math.Exp((rho * sigma - kappa) * T)) / 2.0 / (kappa - rho * sigma);
// Required quantities for f2
double ImC2 = -(Math.Exp(-kappa * T) * theta * kappa + theta * kappa * (kappa * T - 1.0)) / 2.0 / kappa / kappa;
double ImD2 = -(1.0 - Math.Exp(-kappa * T / 2.0)) / 2.0 / kappa;
double pi = Math.PI;
double[] y = new double[N];
double[] z = new double[N];
HestonPrice HP = new HestonPrice();
for (int u = 0; u <= N - 1; u++)
{
// Transformation of the abscissa from [-1,1] to [0,1]
double x = 0.5 * X[u] + 0.5;
if (x == 0.0)
{
// Integrand at left abscissa 0
y[u] = 0.5 * (F - K);
}
else if (x == 1.0)
{
// Integrand at right abscissa 1
double f1 = Math.Log(F / K) + ImC1 + ImD1 * v0;
double f2 = Math.Log(F / K) + ImC2 + ImD2 * v0;
y[u] = 0.5 * (F - K) + (F * f1 - K * f1) / (pi * Cinf);
}
else
{
// Integrand at remaining abscissas
double f1 = HP.HestonProb(-Math.Log(x) / Cinf, param, settings, 1);
double f2 = HP.HestonProb(-Math.Log(x) / Cinf, param, settings, 2);
y[u] = 0.5 * (F - K) + (F * f1 - K * f2) / (x * pi * Cinf);
}
// Multiply by the weights
z[u] = W[u] * y[u];
}
// The Call price
double HCall = Math.Exp(-r * T) * 0.5 * z.Sum();
// The put price by put call parity
if (PutCall == "C")
{
return(HCall);
}
else
{
return(HCall - S * Math.Exp(-q * T) + K * Math.Exp(-r * T));
}
}
static void Main(string[] args)
{
// 32-point Gauss-Laguerre Abscissas and weights
double[] xGLa = new Double[32];
double[] wGLa = new Double[32];
using (TextReader reader = File.OpenText("../../GaussLaguerre32.txt"))
{
for (int k = 0; k <= 31; k++)
{
string text = reader.ReadLine();
string[] bits = text.Split(' ');
xGLa[k] = double.Parse(bits[0]);
wGLa[k] = double.Parse(bits[1]);
}
}
// 32-point Gauss-Legendre Abscissas and weights
double[] xGLe = new Double[32];
double[] wGLe = new Double[32];
using (TextReader reader = File.OpenText("../../GaussLegendre32.txt"))
{
for (int k = 0; k <= 31; k++)
{
string text = reader.ReadLine();
string[] bits = text.Split(' ');
xGLe[k] = double.Parse(bits[0]);
wGLe[k] = double.Parse(bits[1]);
}
}
// 32-point Gauss-Lobatto Abscissas and weights
double[] xGLo = new Double[32];
double[] wGLo = new Double[32];
using (TextReader reader = File.OpenText("../../GaussLobatto32.txt"))
{
for (int k = 0; k <= 31; k++)
{
string text = reader.ReadLine();
string[] bits = text.Split(' ');
xGLo[k] = double.Parse(bits[0]);
wGLo[k] = double.Parse(bits[1]);
}
}
// Heston parameters
HParam param = new HParam();
param.kappa = 1.0;
param.theta = 0.06;
param.sigma = 0.5;
param.v0 = 0.06;
param.rho = -0.8;
param.lambda = 0.0;
// Option price settings
OpSet settings = new OpSet();
settings.S = 10.0;
settings.K = 7.0;
settings.T = 1.0 / 12.0;
settings.r = 0.06;
settings.q = 0.04;
settings.trap = 1;
settings.PutCall = "C";
// Lower and upper integration limits
double a = 0.0; // Lower Limit for Gauss Legendre
double b = 100.0; // Upper Limit for Gauss Legendre
double A = 1e-5; // Lower Limit for Gauss Lobatto
double B = 100.0; // Upper Limit for Gauss Lobatto
// Initialize the price vectors
HestonPrice HP = new HestonPrice();
KahlJackel KJ = new KahlJackel();
double PriceGLa = HP.HestonPriceGaussLaguerre(param, settings, xGLa, wGLa); // Heston Gauss Laguerre
double PriceGLe = HP.HestonPriceGaussLegendre(param, settings, xGLe, wGLe, a, b); // Heston Gauss Legendre
double PriceGLo = HP.HestonPriceGaussLegendre(param, settings, xGLo, wGLo, A, B); // Heston Gauss Lobatto
double PriceKJ = KJ.HestonPriceKahlJackel(param, settings, xGLo, wGLo); // Kahl Jackel Gauss Lobatto
Console.WriteLine("Kahl Jackel Integration scheme");
Console.WriteLine("Method Price");
Console.WriteLine("-------------------------------------");
Console.WriteLine("Heston Gauss Laguerre {0:F5}", PriceGLa);
Console.WriteLine("Heston Gauss Legendre {0:F5}", PriceGLe);
Console.WriteLine("Heston Gauss Lobatto {0:F5}", PriceGLo);
Console.WriteLine("Kahl Jackel Gauss Lobatto {0:F5}", PriceKJ);
Console.WriteLine("-------------------------------------");
}
