public virtual void test_trinomialTree()
{
int nSteps = 135;
LatticeSpecification[] lattices = new LatticeSpecification[]
{
new CoxRossRubinsteinLatticeSpecification(),
new TrigeorgisLatticeSpecification()
};
double tol = 5.0e-3;
foreach (bool isCall in new bool[] { true, false })
{
foreach (double strike in STRIKES)
{
foreach (double interest in INTERESTS)
{
foreach (double vol in VOLS)
{
foreach (double dividend in DIVIDENDS)
{
OptionFunction function = EuropeanVanillaOptionFunction.of(strike, TIME, PutCall.ofPut(!isCall), nSteps);
double exact = BlackScholesFormulaRepository.price(SPOT, strike, TIME, vol, interest, interest - dividend, isCall);
foreach (LatticeSpecification lattice in lattices)
{
double computed = TRINOMIAL_TREE.optionPrice(function, lattice, SPOT, vol, interest, dividend);
assertEquals(computed, exact, Math.Max(exact, 1d) * tol);
}
}
}
}
}
}
}
//-----------------------------------------------------------------------
private Pair <ImmutableList <double[]>, RecombiningTrinomialTreeData> calibrate(System.Func <DoublesPair, double> impliedVolatilitySurface, double spot, System.Func <double, double> interestRate, System.Func <double, double> dividendRate)
{
double[][] stateValue = new double[nSteps + 1][];
double[] df = new double[nSteps];
double[] timePrim = new double[nSteps + 1];
IList <DoubleMatrix> probability = new List <DoubleMatrix>(nSteps);
int nTotal = (nSteps - 1) * (nSteps - 1) + 1;
double[] timeRes = new double[nTotal];
double[] spotRes = new double[nTotal];
double[] volRes = new double[nTotal];
// uniform grid based on TrigeorgisLatticeSpecification
double volatility = impliedVolatilitySurface(DoublesPair.of(maxTime, spot));
double dt = maxTime / nSteps;
double dx = volatility * Math.Sqrt(3d * dt);
double upFactor = Math.Exp(dx);
double downFactor = Math.Exp(-dx);
double[] adSec = new double[2 * nSteps + 1];
double[] assetPrice = new double[2 * nSteps + 1];
for (int i = nSteps; i > -1; --i)
{
timePrim[i] = dt * i;
if (i == 0)
{
resolveFirstLayer(interestRate, dividendRate, nTotal, dt, spot, adSec, assetPrice, timeRes, spotRes, volRes, df, stateValue, probability);
}
else
{
double zeroRate = interestRate(timePrim[i]);
double zeroDividendRate = dividendRate(timePrim[i]);
double zeroCostRate = zeroRate - zeroDividendRate;
int nNodes = 2 * i + 1;
double[] assetPriceLocal = new double[nNodes];
double[] callOptionPrice = new double[nNodes];
double[] putOptionPrice = new double[nNodes];
int position = i - 1;
double assetTmp = spot * Math.Pow(upFactor, i);
// call options for upper half nodes
for (int j = nNodes - 1; j > position - 1; --j)
{
assetPriceLocal[j] = assetTmp;
double impliedVol = impliedVolatilitySurface(DoublesPair.of(timePrim[i], assetPriceLocal[j]));
callOptionPrice[j] = BlackScholesFormulaRepository.price(spot, assetPriceLocal[j], timePrim[i], impliedVol, zeroRate, zeroCostRate, true);
assetTmp *= downFactor;
}
// put options for lower half nodes
assetTmp = spot * Math.Pow(downFactor, i);
for (int j = 0; j < position + 2; ++j)
{
assetPriceLocal[j] = assetTmp;
double impliedVol = impliedVolatilitySurface(DoublesPair.of(timePrim[i], assetPriceLocal[j]));
putOptionPrice[j] = BlackScholesFormulaRepository.price(spot, assetPriceLocal[j], timePrim[i], impliedVol, zeroRate, zeroCostRate, false);
assetTmp *= upFactor;
}
resolveLayer(interestRate, dividendRate, i, nTotal, position, dt, zeroRate, zeroDividendRate, callOptionPrice, putOptionPrice, adSec, assetPrice, assetPriceLocal, timeRes, spotRes, volRes, df, stateValue, probability);
}
}
ImmutableList <double[]> localVolData = ImmutableList.of(timeRes, spotRes, volRes);
RecombiningTrinomialTreeData treeData = RecombiningTrinomialTreeData.of(DoubleMatrix.ofUnsafe(stateValue), probability, DoubleArray.ofUnsafe(df), DoubleArray.ofUnsafe(timePrim));
return(Pair.of(localVolData, treeData));
}
