我希望完全理解Quantlib的求解器如何在给定预测期限结构和折扣期限结构的情况下计算浮动利率债券的Z差价。要做到这一点，首先我创建了一个简单的辅助类来计算债券的成熟收益率，我将与解算器一起使用（我选择布伦特）来比较收益率计算与BondFunctions :: yield。尽管如此，我得到两个不同的结果，三个样本债券，我不明白为什么。
首先，我创建一个辅助类，使用quantlib的求解器以数字方式计算债券到期的收益率
class ytmsolver{
private:
const Real obsPrice;
const Bond& bondObject;
const Date& date;
DayCounter dayCounter;
Compounding compounding;
Frequency frequency;
public:
//constructor
ytmsolver(const Bond &bond, Real &price, Date &settlementDate, DayCounter& dc, Compounding& comp,
Frequency& freq):bondObject(bond),obsPrice(price),date(settlementDate), dayCounter(dc),
compounding(comp),frequency(freq){};
//overloaded operator to be used in the solver
Real operator()(const Rate& rate)const{
return (bondObject.cleanPrice(rate,dayCounter,compounding,frequency)-obsPrice);
}
};
然后我创建了一个浮动利率债券工厂，它创建了一个带有索引的浮动工具，一个预设的期限结构（假设目前为简单计算是平的）和定价引擎。
FloatingRateBond flatTermStructureFloaterFactory(Natural indexTenor, Frequency freq, Date tradeDate,
Date settlementDate,Natural settlementDays, Real faceAmount, const Schedule &schedule,
const Calendar& calendar,const Real ¤tLiborFixing,const Real& lastResetDateLiborFixing,
const DayCounter &accrualDayCounter,
BusinessDayConvention paymentConvention=Following, Natural fixingDays=Null< Natural >(),
const std::vector< Real > &gearings=std::vector< Real >(1, 1.0),
const std::vector< Spread > &spreads=std::vector< Spread >(1, 0.0),
const std::vector< Rate > &caps=std::vector< Rate >(),
const std::vector< Rate > &floors=std::vector< Rate >(),
bool inArrears=false, Real redemption=100.0, const Date &issueDate=Date()){
//***********Term structure declaration***********
//term structure for the cash flows using a libor index
RelinkableHandle<YieldTermStructure> liborTermStructure;
//Libor index which is tied to the Frequency of payments or index tenor
boost::shared_ptr<IborIndex> libor(new USDLibor(Period(indexTenor,Months),liborTermStructure));
//term structure to forecast rest of cash flows
boost::shared_ptr<YieldTermStructure> flatforecast(
new FlatForward(settlementDate, currentLiborFixing, accrualDayCounter, Simple, freq));
liborTermStructure.linkTo(flatforecast);
//Relinkable handle to assign to the price engine.
RelinkableHandle<YieldTermStructure> discountingTermStructure;
//***********Bond object creation***********
FloatingRateBond floatingRateBondInstance(settlementDays, faceAmount,
schedule, libor, accrualDayCounter,
paymentConvention, fixingDays,
// gearings
gearings,
// spreads
spreads);
//*********Finds the last reset date****************
Date lastResetDate;
Leg cashflows=floatingRateBondInstance.cashflows();
/*
Finds the last reset date by browsing through the cashflow dates and offsetting them by
the number of fixing days and a provided calendar.
(ONLY WORKS WITH BONDS WITH THE SAME INDEX AS PERIODICITY)
If this date is provided by the flat file then this search is completely unnecessary
*/
for (Size i=0; i<cashflows.size()-1; i++) {
//Takes the lastResetDate to be the las ocurred date prior the the tradeDate
if ((cashflows[i]->hasOccurred(tradeDate, true))) {
lastResetDate=calendar.advance(cashflows[i]->date(),-fixingDays, Days,paymentConvention);
//cout<<lastResetDate<<endl; //used to print the dates as a debug method.
}
}
cout<<"lastResetDate: "<<lastResetDate<<endl; //prints it to ensure that its correct.
//*********Adds the previous libor rate associated to the last reset date*************
libor->addFixing(lastResetDate, lastResetDateLiborFixing); //last reset date minus fixing days
//***********Bond Engine declaration***********
boost::shared_ptr<PricingEngine> bondEngine(new DiscountingBondEngine (discountingTermStructure));
floatingRateBondInstance.setPricingEngine(bondEngine); //setting the pricing engine for the bond
return floatingRateBondInstance;
}
在此之后我创建了一个简单的函数，它调用了Quantlib的键函数并计算了键的收益率（我用它来计算给定浮动利率债券的收益率。
Real priceToYieldFlatTermStructure(const Bond& bond,
Real cleanPrice,
const DayCounter& dayCounter,
Compounding compounding,
Frequency frequency,
Date settlement,
Real accuracy=1e-50,
Size maxIterations=10000){
//Calls the bond function yield which takes a bond, a clean price, a day count, a compounding,
//a frequency of payments, a settlement date, a degree of accuracy and the number of max iterations to
//reach the yield.
Real irr=BondFunctions::yield(bond,cleanPrice,dayCounter,compounding,frequency,
settlement,accuracy,maxIterations);
return irr;
}
然后我尝试使用Quantlib的求解器以低廉的价格获得这些债券的收益率，并使用以下代码得到不同的结果：
int main(){
try {
Brent solver;
Real accuracy=1e-30, guess=0.00, min=-1.0, max=0.5;
cout<<"*******************************************"<<endl;
cout<<"Bond # 1: US4042Q0HC65"<<endl;
cout<<"*******************************************"<<endl;
//***********Input declaration***********
Natural settlementDays = 3;
Natural fixingdays=2;
Natural indexTenor=6;
Date tradeDate(02,Mar,2015);
Date issueDate(9,Aug,2006);
Date maturityDate(22,Aug,2016);
Real resetMargin=0.016;
Real indexMultiplier=1.0;
Frequency frequency=Semiannual;
Calendar holidayCalendar=UnitedStates(UnitedStates::NYSE);
BusinessDayConvention businessDayConvention= BusinessDayConvention(ModifiedFollowing);
DayCounter dayCounter=Actual360();
Real lastResetDateLiborFixing=0.003853;
Real currentLiborFixing=0.003842;
Real redemption=100;
string settlementcode="BDY"; //internal settlementcode
string settlementvalue="3"; //internal settlementvalue
Date settlementDate=getSettlementDate(tradeDate,holidayCalendar,settlementcode,settlementvalue); //function call to get the settlement date (this is working properly)
cout<<"settlementDate :"<<settlementDate<<endl;
Compounding compounding=Compounded;
Real faceAmount = redemption;
Real obsprice=101.431;
Schedule schedule(issueDate, maturityDate, Period(frequency),
holidayCalendar, businessDayConvention, businessDayConvention,
DateGeneration::Backward, true);
//***********Bond creation to be priced***********
FloatingRateBond floatingRateBondInstance1=flatTermStructureFloaterFactory(indexTenor,frequency,tradeDate,settlementDate,
settlementDays,faceAmount,schedule,holidayCalendar,currentLiborFixing,lastResetDateLiborFixing,
dayCounter,businessDayConvention,fixingdays,std::vector<Real>(1, indexMultiplier),
std::vector<Rate>(1, resetMargin));
Real ytm=priceToYieldFlatTermStructure(floatingRateBondInstance1,obsprice,dayCounter,compounding,frequency,settlementDate);
//***********Bond pricing, yield and discount marging computation***********
cout<<"Clean price: "<<floatingRateBondInstance1.cleanPrice(ytm,dayCounter,compounding,frequency,settlementDate)<<endl;
cout<<"Dirty price: "<<floatingRateBondInstance1.dirtyPrice(ytm,dayCounter,compounding,frequency,settlementDate)<<endl;
cout<<"Accrued interest: "<<floatingRateBondInstance1.accruedAmount(settlementDate)<<endl;
cout<<"Yield: "<<ytm*100<<"%"<<endl;
cout<<"Discount Margin: "<<(ytm-currentLiborFixing)*100<<"%"<<endl;
//***************solver testing***************
Real irr=solver.solve(ytmsolver(floatingRateBondInstance1,obsprice,settlementDate,dayCounter,
compounding,frequency),accuracy,guess,min,max);
cout<<"irr: "<<irr*100<<"%"<<endl;
cout<<"*******************************************"<<endl;
cout<<"Bond # 2: US4042Q0HB82"<<endl;
cout<<"*******************************************"<<endl;
//***********Input declaration***********
indexTenor=6;
issueDate=Date(27,Jul,2006);
maturityDate=Date(20,Jul,2016);
resetMargin=0.0151;
indexMultiplier=1.0;
frequency=Semiannual;
holidayCalendar=TARGET();
//holidayCalendar=UnitedStates(UnitedStates::NYSE); //not counting martin luther king day, jan 15,15 as last reset date
businessDayConvention=BusinessDayConvention(ModifiedFollowing);
dayCounter=Actual360();
lastResetDateLiborFixing=0.003549;
currentLiborFixing=0.003842;
redemption=100;
settlementcode="BDY"; //internal settlement code
settlementvalue="3"; //internal settlement value
settlementDate=getSettlementDate(tradeDate,holidayCalendar,settlementcode,settlementvalue); //function call to get the settlement date (this is working properly)
cout<<"settlementDate :"<<settlementDate<<endl;
compounding=Compounded;
faceAmount = redemption;
obsprice=100.429;
schedule=Schedule(issueDate, maturityDate, Period(frequency),
holidayCalendar, businessDayConvention, businessDayConvention,
DateGeneration::Backward, true);
//***********Bond creation to be priced***********
FloatingRateBond floatingRateBondInstance2=flatTermStructureFloaterFactory(indexTenor,frequency,tradeDate,settlementDate,
settlementDays,faceAmount,schedule,holidayCalendar,currentLiborFixing,lastResetDateLiborFixing,
dayCounter,businessDayConvention,fixingdays,std::vector<Real>(1, indexMultiplier),
std::vector<Rate>(1, resetMargin));
ytm=priceToYieldFlatTermStructure(floatingRateBondInstance2,obsprice,dayCounter,compounding,frequency,settlementDate);
//***********Bond pricing, yield and discount marging computation***********
cout<<"Clean price: "<<floatingRateBondInstance2.cleanPrice(ytm,dayCounter,compounding,frequency,settlementDate)<<endl;
cout<<"Dirty price: "<<floatingRateBondInstance2.dirtyPrice(ytm,dayCounter,compounding,frequency,settlementDate)<<endl;
cout<<"Accrued interest: "<<floatingRateBondInstance2.accruedAmount(settlementDate)<<endl;
cout<<"Yield: "<<ytm*100<<"%"<<endl;
cout<<"Discount Margin: "<<(ytm-currentLiborFixing)*100<<"%"<<endl;
//***************solver testing***************
irr=solver.solve(ytmsolver(floatingRateBondInstance2,obsprice,settlementDate,dayCounter,
compounding,frequency),accuracy,guess,min,max);
cout<<"irr: "<<irr*100<<"%"<<endl;
cout<<"*******************************************"<<endl;
cout<<"Bond # 3: US59022CCT80"<<endl;
cout<<"*******************************************"<<endl;
//***********Input declaration***********
indexTenor=3;
tradeDate=Date(10,Jun,2015);
issueDate=Date(02,May,2007);
maturityDate=Date(02,May,2017);
resetMargin=0.0055;
indexMultiplier=1.0;
frequency=Quarterly;
holidayCalendar=UnitedStates(UnitedStates::NYSE); //not counting martin luther kind day, jan 15,15 as last reset date
businessDayConvention=BusinessDayConvention(ModifiedFollowing);
dayCounter=Actual360();
lastResetDateLiborFixing=0.0027875;
currentLiborFixing=0.0028785;
redemption=100;
settlementcode="BDY"; //internal settlement code
settlementvalue="3"; //internal settlement value
settlementDate=getSettlementDate(tradeDate,holidayCalendar,settlementcode,settlementvalue); //function call to get the settlement date (this is working properly)
cout<<"settlementDate :"<<settlementDate<<endl;
compounding=Compounded;
faceAmount = redemption;
obsprice=99.794;
schedule=Schedule(issueDate, maturityDate, Period(frequency),
holidayCalendar, businessDayConvention, businessDayConvention,
DateGeneration::Backward, true);
//***********Bond pricing, yield and discount marging computation***********
FloatingRateBond floatingRateBondInstance3=flatTermStructureFloaterFactory(indexTenor,frequency,tradeDate,settlementDate,
settlementDays,faceAmount,schedule,holidayCalendar,currentLiborFixing,lastResetDateLiborFixing,
dayCounter,businessDayConvention,fixingdays,std::vector<Real>(1, indexMultiplier),
std::vector<Rate>(1, resetMargin));
ytm=priceToYieldFlatTermStructure(floatingRateBondInstance3,obsprice,dayCounter,compounding,frequency,settlementDate);
//***********Bond pricing, yield and discount marging computation***********
cout<<"Clean price: "<<floatingRateBondInstance3.cleanPrice(ytm,dayCounter,compounding,frequency,settlementDate)<<endl;
cout<<"Dirty price: "<<floatingRateBondInstance3.dirtyPrice(ytm,dayCounter,compounding,frequency,settlementDate)<<endl;
cout<<"Accrued interest: "<<floatingRateBondInstance3.accruedAmount(settlementDate)<<endl;
cout<<"Yield: "<<ytm*100<<"%"<<endl;
cout<<"Discount Margin: "<<(ytm-currentLiborFixing)*100<<"%"<<endl;
//***************solver testing***************
irr=solver.solve(ytmsolver(floatingRateBondInstance3,obsprice,settlementDate,dayCounter,
compounding,frequency),accuracy,guess,min,max);
cout<<"irr: "<<irr*100<<"%"<<endl;
return 0;
} catch (exception& e) {
cerr << e.what() << endl;
return 1;
} catch (...) {
cerr << "unknown error" << endl;
return 1;
}
}
最后我得到了以下结果：
Bond＃1：US4042Q0HC65
和解日期：2015年3月5日 lastResetDate：2015年2月19日 干净价格：101.431 脏价：101.486 应计利息：0.0551472 收益率：1.01286％ 折扣保证金：0.628665％ irr：0.72216％
Bond＃2：US4042Q0HB82
和解日期：2015年3月5日 lastResetDate：2015年1月16日 干净价格：100.429 脏价：100.657 应计利息：0.227932 收益率：1.57325％ 折扣保证金：1.18905％ irr：1.47977％
Bond＃3：US59022CCT80
和解日期：2015年6月15日 lastResetDate：2015年4月30日 干净价格：99.794 脏价：99.8907 应计利息：0.0966875 收益率：0.945517％ 折扣保证金：0.657667％ irr：0.949541％
我在这里做错了什么？我不明白为什么求解器没有返回与屈服的键合函数相同的数字。关于为什么或我在这里做错了什么想法？
答案 0 :(得分：1)
我将假设QuantLib BondFunctions::yield函数返回的结果是正确的，因为当您将其传递给债券的cleanPrice方法时，您会收到您所观察到的价格用作输入。
这让我们猜到你的功能有什么不对。通过查看您的ytmsolver课程，我注意到您没有将结算日期传递给绑定对象的cleanPrice方法，就像重新定位时main中所做的那样。代码。
如果缺少结算日期，该方法会假定它是今天的结算日期 - 即从今天起的三个工作日。这明显晚于您想要的结算日期以及您在main函数中输出的结果日期，因此您得到了错误的收益。将结算日期传递给cleanPrice后，解算器将返回预期值。