private double calculateSinglePeriodAccrualOnDefault(int paymentIndex, PiecewiseconstantHazardRate creditCurve)
{
double[] knots = _premLegIntPoints[paymentIndex];
if (knots == null)
{
return(0.0);
}
double[] df = _premDF[paymentIndex];
double[] deltaT = _premDt[paymentIndex];
double[] rt = _rt[paymentIndex];
double accRate = _accRate[paymentIndex];
double accStart = _offsetAccStart[paymentIndex];
double t = knots[0];
double ht0 = creditCurve.getRT_(t);
double rt0 = rt[0];
double b0 = df[0] * Math.Exp(-ht0);
double t0 = t - accStart + _omega;
double pv = 0.0;
int nItems = knots.Length;
for (int j = 1; j < nItems; ++j)
{
t = knots[j];
double ht1 = creditCurve.getRT_(t);
double rt1 = rt[j];
double b1 = df[j] * Math.Exp(-ht1);
double dt = deltaT[j - 1];
double dht = ht1 - ht0;
double drt = rt1 - rt0;
double dhrt = dht + drt + 1e-50; // to keep consistent with ISDA c code
double tPV;
if (Math.Abs(dhrt) < 1e-5)
{
tPV = dht * dt * b0 * Epsilon.epsilonP(-dhrt);
}
else
{
tPV = dht * dt / dhrt * ((b0 - b1) / dhrt - b1);
}
}
return(accRate * pv);
}
// computes accrual-on-default pv per unit notional for a single payment period
private double singlePeriodAccrualOnDefault(CreditCouponPaymentPeriod coupon, LocalDate effectiveStartDate, DoubleArray integrationSchedule, CreditDiscountFactors discountFactors, LegalEntitySurvivalProbabilities survivalProbabilities)
{
LocalDate start = coupon.EffectiveStartDate.isBefore(effectiveStartDate) ? effectiveStartDate : coupon.EffectiveStartDate;
if (!start.isBefore(coupon.EffectiveEndDate))
{
return(0d); // this coupon has already expired
}
DoubleArray knots = DoublesScheduleGenerator.truncateSetInclusive(discountFactors.relativeYearFraction(start), discountFactors.relativeYearFraction(coupon.EffectiveEndDate), integrationSchedule);
double t0Knot = knots.get(0);
double ht0 = survivalProbabilities.zeroRate(t0Knot) * t0Knot;
double rt0 = discountFactors.zeroRate(t0Knot) * t0Knot;
double b0 = Math.Exp(-rt0 - ht0);
double effStart = discountFactors.relativeYearFraction(coupon.EffectiveStartDate);
double t0 = t0Knot - effStart + omega;
double pv = 0d;
//JAVA TO C# CONVERTER WARNING: The original Java variable was marked 'final':
//ORIGINAL LINE: final int nItems = knots.size();
int nItems = knots.size();
for (int j = 1; j < nItems; ++j)
{
double t = knots.get(j);
double ht1 = survivalProbabilities.zeroRate(t) * t;
double rt1 = discountFactors.zeroRate(t) * t;
double b1 = Math.Exp(-rt1 - ht1);
double dt = knots.get(j) - knots.get(j - 1);
double dht = ht1 - ht0;
double drt = rt1 - rt0;
double dhrt = dht + drt;
double tPV;
if (formula == AccrualOnDefaultFormula.MARKIT_FIX)
{
if (Math.Abs(dhrt) < SMALL)
{
tPV = dht * dt * b0 * Epsilon.epsilonP(-dhrt);
}
else
{
tPV = dht * dt / dhrt * ((b0 - b1) / dhrt - b1);
}
}
else
{
double t1 = t - effStart + omega;
if (Math.Abs(dhrt) < SMALL)
{
tPV = dht * b0 * (t0 * epsilon(-dhrt) + dt * Epsilon.epsilonP(-dhrt));
}
else
{
tPV = dht / dhrt * (t0 * b0 - t1 * b1 + dt / dhrt * (b0 - b1));
}
t0 = t1;
}
pv += tPV;
ht0 = ht1;
rt0 = rt1;
b0 = b1;
}
double yearFractionCurve = discountFactors.DayCount.relativeYearFraction(coupon.StartDate, coupon.EndDate);
return(coupon.YearFraction * pv / yearFractionCurve);
}