/// <summary>
/// Calculates the present value of the swaption product.
/// <para>
/// The result is expressed using the currency of the swapion.
///
/// </para>
/// </summary>
/// <param name="swaption"> the product </param>
/// <param name="ratesProvider"> the rates provider </param>
/// <param name="hwProvider"> the Hull-White model parameter provider </param>
/// <returns> the present value </returns>
public virtual CurrencyAmount presentValue(ResolvedSwaption swaption, RatesProvider ratesProvider, HullWhiteOneFactorPiecewiseConstantParametersProvider hwProvider)
{
validate(swaption, ratesProvider, hwProvider);
ResolvedSwap swap = swaption.Underlying;
LocalDate expiryDate = swaption.ExpiryDate;
if (expiryDate.isBefore(ratesProvider.ValuationDate))
{ // Option has expired already
return(CurrencyAmount.of(swap.Legs.get(0).Currency, 0d));
}
ResolvedSwapLeg cashFlowEquiv = CashFlowEquivalentCalculator.cashFlowEquivalentSwap(swap, ratesProvider);
int nPayments = cashFlowEquiv.PaymentEvents.size();
double[] alpha = new double[nPayments];
double[] discountedCashFlow = new double[nPayments];
for (int loopcf = 0; loopcf < nPayments; loopcf++)
{
NotionalExchange payment = (NotionalExchange)cashFlowEquiv.PaymentEvents.get(loopcf);
LocalDate maturityDate = payment.PaymentDate;
alpha[loopcf] = hwProvider.alpha(ratesProvider.ValuationDate, expiryDate, expiryDate, maturityDate);
discountedCashFlow[loopcf] = paymentPricer.presentValueAmount(payment.Payment, ratesProvider);
}
double omega = (swap.getLegs(SwapLegType.FIXED).get(0).PayReceive.Pay ? -1d : 1d);
double kappa = computeKappa(hwProvider, discountedCashFlow, alpha, omega);
double pv = 0.0;
for (int loopcf = 0; loopcf < nPayments; loopcf++)
{
pv += discountedCashFlow[loopcf] * NORMAL.getCDF(omega * (kappa + alpha[loopcf]));
}
return(CurrencyAmount.of(cashFlowEquiv.Currency, pv * (swaption.LongShort.Long ? 1d : -1d)));
}
//-------------------------------------------------------------------------
public virtual void test_presentValue()
{
CurrencyAmount computedRec = PRICER.presentValue(SWAPTION_REC_LONG, RATE_PROVIDER, HW_PROVIDER);
CurrencyAmount computedPay = PRICER.presentValue(SWAPTION_PAY_SHORT, RATE_PROVIDER, HW_PROVIDER);
SwapPaymentEventPricer <SwapPaymentEvent> paymentEventPricer = SwapPaymentEventPricer.standard();
ResolvedSwapLeg cashFlowEquiv = CashFlowEquivalentCalculator.cashFlowEquivalentSwap(RSWAP_REC, RATE_PROVIDER);
LocalDate expiryDate = MATURITY.toLocalDate();
int nPayments = cashFlowEquiv.PaymentEvents.size();
double[] alpha = new double[nPayments];
double[] discountedCashFlow = new double[nPayments];
for (int loopcf = 0; loopcf < nPayments; loopcf++)
{
SwapPaymentEvent payment = cashFlowEquiv.PaymentEvents.get(loopcf);
alpha[loopcf] = HW_PROVIDER.alpha(RATE_PROVIDER.ValuationDate, expiryDate, expiryDate, payment.PaymentDate);
discountedCashFlow[loopcf] = paymentEventPricer.presentValue(payment, RATE_PROVIDER);
}
double omegaPay = -1d;
double kappa = HW_PROVIDER.Model.kappa(DoubleArray.copyOf(discountedCashFlow), DoubleArray.copyOf(alpha));
double expectedRec = 0.0;
double expectedPay = 0.0;
for (int loopcf = 0; loopcf < nPayments; loopcf++)
{
expectedRec += discountedCashFlow[loopcf] * NORMAL.getCDF((kappa + alpha[loopcf]));
expectedPay += discountedCashFlow[loopcf] * NORMAL.getCDF(omegaPay * (kappa + alpha[loopcf]));
}
assertEquals(computedRec.Currency, EUR);
assertEquals(computedRec.Amount, expectedRec, NOTIONAL * TOL);
assertEquals(computedPay.Currency, EUR);
assertEquals(computedPay.Amount, expectedPay, NOTIONAL * TOL);
}
//-------------------------------------------------------------------------
/// <summary>
/// Calculates the present value sensitivity to piecewise constant volatility parameters of the Hull-White model.
/// </summary>
/// <param name="swaption"> the product </param>
/// <param name="ratesProvider"> the rates provider </param>
/// <param name="hwProvider"> the Hull-White model parameter provider </param>
/// <returns> the present value Hull-White model parameter sensitivity of the swaption product </returns>
public virtual DoubleArray presentValueSensitivityModelParamsHullWhite(ResolvedSwaption swaption, RatesProvider ratesProvider, HullWhiteOneFactorPiecewiseConstantParametersProvider hwProvider)
{
validate(swaption, ratesProvider, hwProvider);
ResolvedSwap swap = swaption.Underlying;
LocalDate expiryDate = swaption.ExpiryDate;
if (expiryDate.isBefore(ratesProvider.ValuationDate))
{ // Option has expired already
return(DoubleArray.EMPTY);
}
ResolvedSwapLeg cashFlowEquiv = CashFlowEquivalentCalculator.cashFlowEquivalentSwap(swap, ratesProvider);
int nPayments = cashFlowEquiv.PaymentEvents.size();
double[] alpha = new double[nPayments];
double[][] alphaAdjoint = new double[nPayments][];
double[] discountedCashFlow = new double[nPayments];
for (int loopcf = 0; loopcf < nPayments; loopcf++)
{
NotionalExchange payment = (NotionalExchange)cashFlowEquiv.PaymentEvents.get(loopcf);
ValueDerivatives valueDeriv = hwProvider.alphaAdjoint(ratesProvider.ValuationDate, expiryDate, expiryDate, payment.PaymentDate);
alpha[loopcf] = valueDeriv.Value;
alphaAdjoint[loopcf] = valueDeriv.Derivatives.toArray();
discountedCashFlow[loopcf] = paymentPricer.presentValueAmount(payment.Payment, ratesProvider);
}
double omega = (swap.getLegs(SwapLegType.FIXED).get(0).PayReceive.Pay ? -1d : 1d);
double kappa = computeKappa(hwProvider, discountedCashFlow, alpha, omega);
int nParams = alphaAdjoint[0].Length;
if (Math.Abs(kappa) > 1d / SMALL)
{ // decays exponentially
return(DoubleArray.filled(nParams));
}
double[] pvSensi = new double[nParams];
double sign = (swaption.LongShort.Long ? 1d : -1d);
for (int i = 0; i < nParams; ++i)
{
for (int loopcf = 0; loopcf < nPayments; loopcf++)
{
pvSensi[i] += sign * discountedCashFlow[loopcf] * NORMAL.getPDF(omega * (kappa + alpha[loopcf])) * omega * alphaAdjoint[loopcf][i];
}
}
return(DoubleArray.ofUnsafe(pvSensi));
}