private static TermStructure CalcCurveFromMaturity(DateTime Maturity, DateTime StartDate, double CouponRate,
NextWorkingDayConvention nextDay, int Freq, Dictionary <DateTime, DateTime> Holidays,
bool FixedCashPayments)
{
List <TermPoint> points = new List <TermPoint>();
DateTime pointDate = Maturity;
bool lastPoint = true;
while (pointDate > StartDate)
{
if (lastPoint)
{
// Only do the last point once, decrement the date next time around
lastPoint = false;
}
else
{
pointDate = pointDate.AddMonths(-(12 / Freq));
}
TermPoint point = new TermPoint();
point.Rate = CouponRate;
point.PointDate = pointDate;
int month = point.PointDate.Month;
point.PayDate = GetWorkingDayDate(1, pointDate.AddDays(-1), Holidays, nextDay);
if (!FixedCashPayments)
{
point.PointDate = point.PayDate;
}
points.Add(point);
}
;
TermStructure ts = new TermStructure();
for (int i = points.Count - 1; i >= 0; i--)
{
ts.Points.Add(points[i]);
}
return(ts);
}
private void BootstrapSwapRates(InputData inputData)
{
// prev rate starts off as the most recent Future rate
Rate prev = inputData.FutureData[inputData.FutureData.Count - 1];
foreach (Rate rate in inputData.SwapData)
{
double fixedCoupon = rate.SwapRate / 100;
DateTime lastDate = rate.TermDate.AddMonths(-12 / inputData.SwapFixedPaymentFrequency);
TermStructure ts = Functions.GetTermStructure(lastDate, rate.StartDate, rate.StartDate, fixedCoupon,
inputData.SwapFixedDayCountConvention, inputData.NextWorkingDay, inputData.SwapFixedPaymentFrequency, inputData.Holidays, false);
ts.PrintStructure();
double fixedCash = Functions.PresentValue(rate.StartDate, 0, ts, inputData, inputData.Holidays, false);
ts = Functions.GetTermStructure(rate.TermDate, lastDate, lastDate, fixedCoupon,
inputData.SwapFixedDayCountConvention, inputData.NextWorkingDay, inputData.SwapFixedPaymentFrequency, inputData.Holidays, false);
ts.PrintStructure();
double accrued = 1 + Functions.AccruedForDaysInPeriod(lastDate, rate.TermDate, ts, fixedCoupon, false);
double discountFactor = 0;
accrued = accrued > 0 ? discountFactor = (1 - fixedCash) / accrued : 1 - fixedCash;
// Adjust rates to curve basis
if (inputData.DayCountConvention != inputData.SwapFixedDayCountConvention)
{
rate.Term = Functions.DaysBetween(rate.StartDate, rate.TermDate, inputData.DayCountConvention);
}
rate.SpotRate = 100 * Functions.GetRateFromDiscountFactor(discountFactor, rate.Term, Functions.DaysInYear(inputData.DayCountConvention));
inputData.Rates.Add(rate);
}
}
internal static double AccruedForDaysInPeriod(DateTime AccrueFrom, DateTime AccrueTo, TermStructure ts, double Rate, bool FixedCashPayments)
{
double ret = 0;
TermPoint periodStart = ts.Points[0];
TermPoint periodEnd = null;
if (AccrueTo > ts.Points[0].PointDate && AccrueFrom < ts.Points[ts.PointCount - 1].PointDate)
{
// Find the applicable period
foreach (TermPoint point in ts.Points)
{
if (point.PointDate <= AccrueFrom)
{
periodStart = point;
}
else if (point.PointDate >= AccrueTo)
{
periodEnd = point;
break;
}
}
// If the caller has asked for Accrued to a point past the end of the term structure it is not valid
// and the PeriodEnd variable will be equal to zero
if (periodEnd == null)
{
throw new Exception(string.Format("AccrueTo data [{0}] is past the end of the curve [{1}].", AccrueTo.ToString("dd MMM yy"), ts.Points[ts.PointCount - 1].PointDate.ToString("dd MMM yy")));
}
int days = DaysBetween(AccrueFrom, AccrueTo, ts.DayCount);
int periodLength = DaysBetween(periodStart.PointDate, periodEnd.PointDate, ts.DayCount);
int freq = (int)Math.Round((double)365 / periodLength, 0);
// We need to get the rate of the point to which we are accrueing up to
// A rate quoted within the Curve is the portion of rate for that period. So the rate according to the curve for a
// semi annual bond paying 5% would be 2.5%
if (Rate == 0)
{
Rate = periodEnd.Amount;
}
if (FixedCashPayments)
{
if (periodLength > 366)
{
// it's longer than a year.
// We need to work out the accrued as if a coupon "was" paid each year
// This will take account of when a Feb 29 occurrs
// Split the accrued to before and after an imaginary paydate being one year before the real pay date
DateTime couponPoint2 = periodEnd.PointDate;
do
{
DateTime couponPoint = couponPoint2.AddYears(-1);
periodLength = DaysBetween(couponPoint, couponPoint2, ts.DayCount);
if (couponPoint < AccrueTo)
{
if (couponPoint2 < AccrueTo)
{
// We have done the part up to AccrueTo
if (AccrueFrom < couponPoint)
{
days = DaysBetween(couponPoint, couponPoint2, ts.DayCount);
}
else
{
days = DaysBetween(AccrueFrom, couponPoint, ts.DayCount);
}
}
else
{
// Work out accrued from the CouponPoint to the AccrueTo date
if (AccrueFrom < couponPoint)
{
days = DaysBetween(couponPoint, AccrueTo, ts.DayCount);
}
else
{
days = DaysBetween(AccrueFrom, AccrueTo, ts.DayCount);
}
}
ret += (Rate * days / periodLength);
}
couponPoint2 = couponPoint;
} while (couponPoint2 < AccrueFrom);
}
else
{
if (periodLength != 0)
{
ret += (Rate / freq) * (days / periodLength);
}
}
}
else
{
switch (ts.DayCount)
{
case DayCountConvention.e30_360:
case DayCountConvention.e30E_360:
case DayCountConvention.e30E1_360:
case DayCountConvention.eActual_360:
ret = Rate * days / 360;
break;
case DayCountConvention.eActual_365:
case DayCountConvention.eActualNL_365:
ret = Rate * days / 365;
break;
case DayCountConvention.eActual_Actual:
// Check for leap years
int year1 = (int)DateTime.Parse("1 Jan " + AccrueTo.AddYears(1).Year).Subtract(DateTime.Parse("1 Jan " + AccrueFrom.Year)).TotalDays;
if (year1 == 731)
{ // it goes into two years one of which is a leap year
// A bit different for this
// This assumes that the period is <= 1 year, ie, cannot span more than 2 adjacent years
// Days = startpoint up to the first of next year
days = (int)DateTime.Parse("1 Jan " + periodEnd.PointDate.Year).Subtract(periodStart.PointDate).TotalDays;
// Days2 = the first of the next year to the end point
int days2 = (int)periodEnd.PointDate.Subtract(DateTime.Parse("1 Jan " + periodEnd.PointDate.Year)).TotalDays;
// Number of days in each seperate period which falls in each year
year1 = (int)DateTime.Parse("1 Jan " + periodEnd.PointDate.Year).Subtract(DateTime.Parse("1 Jan " + periodStart.PointDate.Year)).TotalDays;
int year2 = (int)DateTime.Parse("1 Jan " + periodEnd.PointDate.Year + 1).Subtract(DateTime.Parse("1 Jan " + periodEnd.PointDate.Year)).TotalDays;
ret = (((Rate / year1) * days)) + (((Rate / year2) * days2));
}
else
{
ret = (Rate * days) / year1;
}
break;
}
}
}
return(ret);
}
internal static double PresentValue(DateTime ValueDate, double SpreadOverLibor, TermStructure ts, InputData inputData, Dictionary <DateTime, DateTime> Holidays, bool FixedCashPayments)
{
double ret = 0;
// LastPaymentDate should be the date from which we wish to start accrueing interest.
// This is either the lastcoupon payment (for fixed cash payments) or the Startdate if that is later and not Fixed Cash Payments
// The curve passed in (Rates) would have either the lastcouponpayment or the startdate as the preceding point
DateTime lastPayDate = DateTime.MinValue;
DayCountConvention dayC = ts.DayCount;
foreach (TermPoint point in ts.Points)
{
lastPayDate = point.PointDate;
if (point.PointDate >= ValueDate)
{
break;
}
}
for (int p = 1; p < ts.PointCount; p++)
{
DateTime nextPaymentDate = ts.Points[p].PointDate;
DateTime nextPayDate = ts.Points[p].PayDate;
int daysToDiscount = DaysBetween(ValueDate, nextPayDate, dayC);
if (daysToDiscount > 0)
{
double fixingRate = ts.Points[p].Rate;
double discountFactor = GetDiscountFactor(daysToDiscount, inputData.Rates, dayC);
int daysToAccrue = DaysBetween(lastPayDate, nextPaymentDate, dayC);
double paymentValue = AccruedForDaysInPeriod(ts.Points[p - 1].PointDate, ts.Points[p].PointDate, ts, fixingRate + SpreadOverLibor, FixedCashPayments);
ret += paymentValue * discountFactor;
}
lastPayDate = nextPayDate;
}
return(ret);
}
internal static TermStructure GetTermStructure(DateTime Maturity, DateTime StartDate, DateTime FirstCouponDate, double CouponRate,
DayCountConvention dayCount, NextWorkingDayConvention nextDay, int Freq, Dictionary <DateTime, DateTime> Holidays,
bool FixedCashPayments)
{
TermStructure ts = CalcCurveFromMaturity(Maturity, StartDate, CouponRate, nextDay, Freq, Holidays, false);
ts.DayCount = dayCount;
// Calc daycount depending on accrual rule
int yearDays = DaysInYear(dayCount);
int point;
TermPoint tp;
TermPoint ltp;
for (point = 1; point < ts.PointCount; point++)
{
tp = ts.Points[point];
ltp = ts.Points[point - 1];
tp.Term = DaysBetween(ltp.PointDate, tp.PointDate, dayCount);
if (FixedCashPayments)
{
int lastYear = (int)tp.PointDate.Subtract(tp.PointDate.AddYears(-1)).TotalDays;
if (tp.Term <= yearDays || lastYear == -366)
{
tp.EffectiveRate = tp.Rate / Freq * yearDays / tp.Term;
}
else
{
tp.EffectiveRate = tp.Rate;
}
}
else
{
tp.EffectiveRate = tp.Rate;
}
}
point = 0;
while (point > -1 && ts.PointCount > 1)
{
tp = ts.Points[point];
if (tp.PointDate < StartDate)
{
tp.PointDate = StartDate;
tp = ts.Points[point + 1];
tp.Term = DaysBetween(StartDate, tp.PointDate, dayCount);
}
else if (tp.PointDate > StartDate && tp.PointDate < FirstCouponDate && point != 0)
{
ts.Points.Remove(tp);
if (point < ts.PointCount && point > 0)
{
tp = ts.Points[point];
ltp = ts.Points[point - 1];
tp.Term = DaysBetween(ltp.PointDate, tp.PointDate, dayCount);
}
point--;
}
else if (tp.PointDate >= FirstCouponDate)
{
point = -2; // get out
}
point++;
}
int totalTerm = 0;
for (point = 1; point < ts.PointCount; point++)
{
tp = ts.Points[point];
ltp = ts.Points[point - 1];
// BUT for actual / actual and in a leap year some more calculations need to be done.
// e.g. Period 2 jan 96 to 1 jan 97 = (365/366 + 1/365) NOT including the last day but including the first day
if (dayCount == DayCountConvention.eActual_Actual && FixedCashPayments == false &&
ltp.PointDate.Year != tp.PointDate.Year)
{
tp.YearFraction =
ltp.PointDate.Subtract(DateTime.Parse("1 Jan " + ltp.PointDate.AddYears(1).Year)).TotalDays
/
DateTime.Parse("1 Jan " + ltp.PointDate.AddYears(1).Year).Subtract(DateTime.Parse("1 Jan " + ltp.PointDate.Year)).TotalDays
+
tp.PointDate.Subtract(DateTime.Parse("1 Jan " + tp.PointDate.Year)).TotalDays
/
DateTime.Parse("1 Jan " + tp.PointDate.AddYears(1).Year).Subtract(DateTime.Parse("1 Jan " + tp.PointDate.Year)).TotalDays;
}
else
{
if (tp.Rate > 0 && FixedCashPayments)
{
tp.YearFraction = tp.EffectiveRate * tp.Term / yearDays / tp.Rate;
}
else
{
tp.YearFraction = (double)tp.Term / (double)yearDays;
}
}
tp.Amount = tp.Rate * tp.YearFraction;
// Reset daycounts to be cummulative
totalTerm += tp.Term;
tp.Term = totalTerm;
}
return(ts);
}
