// helper function used to calculate Time-To-Discount for each stage when calculating discount factor stepwisely
public static double getStepwiseDiscountTime(CashFlow cashFlow, DayCounter dc, Date npvDate, Date lastDate)
{
Date cashFlowDate = cashFlow.date();
Date refStartDate, refEndDate;
Coupon coupon = cashFlow as Coupon;
if (coupon != null)
{
refStartDate = coupon.referencePeriodStart;
refEndDate = coupon.referencePeriodEnd;
}
else
{
if (lastDate == npvDate)
{
// we don't have a previous coupon date,
// so we fake it
refStartDate = cashFlowDate - new Period(1, TimeUnit.Years);
}
else
{
refStartDate = lastDate;
}
refEndDate = cashFlowDate;
}
if (coupon != null && lastDate != coupon.accrualStartDate())
{
double couponPeriod = dc.yearFraction(coupon.accrualStartDate(), cashFlowDate, refStartDate, refEndDate);
double accruedPeriod = dc.yearFraction(coupon.accrualStartDate(), lastDate, refStartDate, refEndDate);
return(couponPeriod - accruedPeriod);
}
else
{
return(dc.yearFraction(lastDate, cashFlowDate, refStartDate, refEndDate));
}
}
public static Date startDate(Leg leg)
{
Utils.QL_REQUIRE(!leg.empty(), () => "empty leg");
Date d = Date.maxDate();
for (int i = 0; i < leg.Count; ++i)
{
Coupon c = leg[i] as Coupon;
if (c != null)
{
d = Date.Min(d, c.accrualStartDate());
}
else
{
d = Date.Min(d, leg[i].date());
}
}
return(d);
}
public static Date accrualStartDate(Leg leg, bool includeSettlementDateFlows, Date settlementDate = null)
{
CashFlow cf = nextCashFlow(leg, includeSettlementDateFlows, settlementDate);
if (cf == null)
{
return(null);
}
Date paymentDate = cf.date();
foreach (CashFlow x in leg.Where(x => x.date() == paymentDate))
{
Coupon cp = x as Coupon;
if (cp != null)
{
return(cp.accrualStartDate());
}
}
return(null);
}
