Real BlackIborCouponPricer::optionletPrice(Option::Type optionType,
Real effStrike) const {
Date fixingDate = coupon_->fixingDate();
if (fixingDate <= Settings::instance().evaluationDate()) {
// the amount is determined
Real a, b;
if (optionType==Option::Call) {
a = coupon_->indexFixing();
b = effStrike;
} else {
a = effStrike;
b = coupon_->indexFixing();
}
return std::max(a - b, 0.0)* accrualPeriod_*discount_;
} else {
// not yet determined, use Black model
QL_REQUIRE(!capletVolatility().empty(),
"missing optionlet volatility");
Real stdDev =
std::sqrt(capletVolatility()->blackVariance(fixingDate,
effStrike));
Real shift = capletVolatility()->displacement();
bool shiftedLn =
capletVolatility()->volatilityType() == ShiftedLognormal;
Rate fixing =
shiftedLn
? blackFormula(optionType, effStrike, adjustedFixing(),
stdDev, 1.0, shift)
: bachelierBlackFormula(optionType, effStrike,
adjustedFixing(), stdDev, 1.0);
return fixing * accrualPeriod_ * discount_;
}
}
Real HullWhiteSmileSection::volatilityImpl(Rate strike) const {
boost::shared_ptr<VanillaSwap> underlying = MakeVanillaSwap(swapLength_,swapIndex_->iborIndex(),strike)
.withEffectiveDate(swapIndex_->valueDate(optionDate_))
.withFixedLegCalendar(swapIndex_->fixingCalendar())
.withFixedLegDayCount(swapIndex_->dayCounter())
.withFixedLegTenor(swapIndex_->fixedLegTenor())
.withFixedLegConvention(swapIndex_->fixedLegConvention())
.withFixedLegTerminationDateConvention(swapIndex_->fixedLegConvention())
.withType(VanillaSwap::Payer);
underlying->setPricingEngine(discountingEngine_);
boost::shared_ptr<Exercise> exercise(new EuropeanExercise(optionDate_));
Swaption swaption(underlying,exercise);
swaption.setPricingEngine(jamshidianEngine_);
Real npv = swaption.NPV();
Real annuity = fabs(underlying->fixedLegBPS() * 10000.0);
//Real blackNpv=blackFormula(Option::Call,strike,atm,0.30*sqrt(exerciseTime()));
//std::cout << std::setprecision(8) << "SECTION atm=" << atm_ << " annuity=" << annuity << " npv=" << npv << " strike= " << strike << std::endl;
Real vol=0.0;
try {
vol=blackFormulaImpliedStdDev(Option::Call,strike,atm_,npv,annuity) / sqrt(exerciseTime());
} catch(QuantLib::Error) {
//std::cout << " can not imply vol for npv " << npv << " black(300%)=" << blackFormula(Option::Call,strike,atm_,sqrt(exerciseTime())*3.00,annuity) <<
// " black(1%)=" << blackFormula(Option::Call,strike,atm_,sqrt(exerciseTime())*0.01,annuity) << std::endl;
if(npv>blackFormula(Option::Call,strike,atm_,3.00,annuity)) vol =3.0/sqrt(exerciseTime());
else vol=0.0;
}
return vol;
}
Real YoYInflationBlackCapFloorEngine::optionletImpl(Option::Type type, Rate strike,
Rate forward, Real stdDev,
Real d) const
{
return blackFormula(type, strike,
forward, stdDev, d);
}
Real HestonModelHelper::blackPrice(Real volatility) const {
calculate();
const Real stdDev = volatility * std::sqrt(maturity());
return blackFormula(
type_, strikePrice_ * termStructure_->discount(tau_),
s0_->value() * dividendYield_->discount(tau_), stdDev);
}
Real blackFormula(const boost::shared_ptr<PlainVanillaPayoff>& payoff,
Real forward,
Real stdDev,
Real discount,
Real displacement) {
return blackFormula(payoff->optionType(),
payoff->strike(), forward, stdDev, discount, displacement);
}
Real YoYInflationUnitDisplacedBlackCapFloorEngine::optionletImpl(
Option::Type type, Rate strike,
Rate forward, Real stdDev,
Real d) const
{
// could use displacement parameter in blackFormula but this is clearer
return blackFormula(type, strike+1.0,
forward+1.0, stdDev, d);
}
Real Generalized_HullWhite::discountBondOption(Option::Type type, Real strike,
Time maturity,
Time bondMaturity) const {
Real _a = a();
Real v;
v = std::sqrt(Vp(0, maturity, bondMaturity));
Real f = termStructure()->discount(bondMaturity);
Real k = termStructure()->discount(maturity)*strike;
return blackFormula(type, k, f, v);
}
Real SmileSection::optionPrice(Rate strike,
Option::Type type,
Real discount) const {
Real atm = atmLevel();
QL_REQUIRE(atm != Null<Real>(),
"smile section must provide atm level to compute option price");
// if lognormal or shifted lognormal,
// for strike at -shift, return option price even if outside
// minstrike, maxstrike interval
if (volatilityType() == ShiftedLognormal)
return blackFormula(type,strike,atm, fabs(strike+shift()) < QL_EPSILON ?
0.2 : sqrt(variance(strike)),discount,shift());
else
return bachelierBlackFormula(type,strike,atm,sqrt(variance(strike)),discount);
}
Real HullWhite::discountBondOption(Option::Type type, Real strike,
Time maturity,
Time bondMaturity) const {
Real _a = a();
Real v;
if (_a < std::sqrt(QL_EPSILON)) {
v = sigma()*B(maturity, bondMaturity)* std::sqrt(maturity);
} else {
v = sigma()*B(maturity, bondMaturity)*
std::sqrt(0.5*(1.0 - std::exp(-2.0*_a*maturity))/_a);
}
Real f = termStructure()->discount(bondMaturity);
Real k = termStructure()->discount(maturity)*strike;
return blackFormula(type, k, f, v);
}
Real HullWhite::discountBondOption(Option::Type type, Real strike,
Time maturity, Time bondStart,
Time bondMaturity) const {
Real _a = a();
Real v;
if (_a < std::sqrt(QL_EPSILON)) {
v = sigma()*B(bondStart, bondMaturity)* std::sqrt(maturity);
} else {
v = sigma()/(_a*sqrt(2.0*_a)) * sqrt (
exp(-2.0*_a*(bondStart-maturity))-exp(-2.0*_a*bondStart)
-2.0*(exp(-_a*(bondStart+bondMaturity-2.0*maturity))-exp(-_a*(bondStart+bondMaturity)))
+exp(-2.0*_a*(bondMaturity-maturity))-exp(-2.0*_a*bondMaturity));
}
Real f = termStructure()->discount(bondMaturity);
Real k = termStructure()->discount(bondStart)*strike;
return blackFormula(type, k, f, v);
}
Real LiborForwardModel::discountBondOption(Option::Type type,
Real strike, Time maturity,
Time bondMaturity) const {
const std::vector<Time> & accrualStartTimes
= process_->accrualStartTimes();
const std::vector<Time> & accrualEndTimes
= process_->accrualEndTimes();
QL_REQUIRE( accrualStartTimes.front()<= maturity
&& accrualStartTimes.back() >= maturity,
"capet maturity does not fit to the process");
const Size i = std::lower_bound(accrualStartTimes.begin(),
accrualStartTimes.end(),
maturity) - accrualStartTimes.begin();
QL_REQUIRE( i<process_->size()
&& std::fabs(maturity - accrualStartTimes[i])
< 100*std::numeric_limits<Real>::epsilon()
&& std::fabs(bondMaturity - accrualEndTimes[i])
< 100*std::numeric_limits<Real>::epsilon(),
"irregular fixings are not (yet) supported");
const Real tenor = accrualEndTimes[i] - accrualStartTimes[i];
const Real forward = process_->initialValues()[i];
const Real capRate = (1.0/strike - 1.0)/tenor;
const Volatility var = covarProxy_
->integratedCovariance(i, i, process_->fixingTimes()[i]);
const DiscountFactor dis =
process_->index()->forwardingTermStructure()->discount(bondMaturity);
const Real black = blackFormula(
(type==Option::Put ? Option::Call : Option::Put),
capRate, forward, std::sqrt(var));
const Real npv = dis * tenor * black;
return npv / (1.0 + capRate*tenor);
}
CapPseudoDerivative::CapPseudoDerivative(boost::shared_ptr<MarketModel> inputModel,
Real strike,
Size startIndex,
Size endIndex, Real firstDF) : firstDF_(firstDF)
{
QL_REQUIRE(startIndex < endIndex, "for a cap pseudo derivative the start of the cap must be before the end");
QL_REQUIRE( endIndex <= inputModel->numberOfRates(), "for a cap pseudo derivative the end of the cap must before the end of the rates");
Size numberCaplets = endIndex-startIndex;
Size numberRates = inputModel->numberOfRates();
Size factors = inputModel->numberOfFactors();
LMMCurveState curve(inputModel->evolution().rateTimes());
curve.setOnForwardRates(inputModel->initialRates());
const Matrix& totalCovariance(inputModel->totalCovariance(inputModel->numberOfSteps()-1));
std::vector<Real> displacedImpliedVols(numberCaplets);
std::vector<Real> annuities(numberCaplets);
std::vector<Real> initialRates(numberCaplets);
std::vector<Real> expiries(numberCaplets);
Real capPrice =0.0;
Real guess=0.0;
Real minVol = 1e10;
Real maxVol =0.0;
for (Size j = startIndex; j < endIndex; ++j)
{
Size capletIndex = j - startIndex;
Time resetTime = inputModel->evolution().rateTimes()[j];
expiries[capletIndex] = resetTime;
Real sd = std::sqrt(totalCovariance[j][j]);
displacedImpliedVols[capletIndex] = std::sqrt(totalCovariance[j][j]/resetTime);
Real forward = inputModel->initialRates()[j];
initialRates[capletIndex] = forward;
Real annuity = curve.discountRatio(j+1,0)* inputModel->evolution().rateTaus()[j]*firstDF_;
annuities[capletIndex] = annuity;
Real displacement = inputModel->displacements()[j];
guess+= displacedImpliedVols[capletIndex]*(forward+displacement)/forward;
minVol =std::min(minVol, displacedImpliedVols[capletIndex]);
maxVol =std::max(maxVol, displacedImpliedVols[capletIndex]*(forward+displacement)/forward);
Real capletPrice = blackFormula(Option::Call,
strike,
forward,
sd,
annuity,
displacement
);
capPrice += capletPrice;
}
guess/=numberCaplets;
for (Size step =0; step < inputModel->evolution().numberOfSteps(); ++step)
{
Matrix thisDerivative(numberRates,factors,0.0);
for (Size rate =std::max(inputModel->evolution().firstAliveRate()[step],startIndex);
rate < endIndex; ++rate)
{
for (Size f=0; f < factors; ++f)
{
Real expiry = inputModel->evolution().rateTimes()[rate];
Real volDerivative = inputModel->pseudoRoot(step)[rate][f]
/(displacedImpliedVols[rate-startIndex]*expiry);
Real capletVega = blackFormulaVolDerivative(strike,inputModel->initialRates()[rate],
displacedImpliedVols[rate-startIndex]*std::sqrt(expiry),
expiry,
annuities[rate-startIndex],
inputModel->displacements()[rate]);
// note that the cap derivative is equal to one of the caplet ones so we lose a loop
thisDerivative[rate][f] = volDerivative*capletVega;
}
}
priceDerivatives_.push_back(thisDerivative);
}
QuickCap capPricer(strike, annuities, initialRates, expiries,capPrice);
Size maxEvaluations = 1000;
Real accuracy = 1E-6;
Brent solver;
solver.setMaxEvaluations(maxEvaluations);
impliedVolatility_ = solver.solve(capPricer,accuracy,guess,minVol*0.99,maxVol*1.01);
vega_ = capPricer.vega(impliedVolatility_);
for (Size step =0; step < inputModel->evolution().numberOfSteps(); ++step)
{
Matrix thisDerivative(numberRates,factors,0.0);
for (Size rate =std::max(inputModel->evolution().firstAliveRate()[step],startIndex);
rate < endIndex; ++rate)
{
for (Size f=0; f < factors; ++f)
{
thisDerivative[rate][f] = priceDerivatives_[step][rate][f]/vega_;
}
}
volatilityDerivatives_.push_back(thisDerivative);
}
}
Real value(const Option::Type type, const Real strike,
const Real atmForward, const Real stdDev, const Real annuity,
const Real displacement) {
return blackFormula(type, strike, atmForward, stdDev, annuity,
displacement);
}
void JuQuadraticApproximationEngine::calculate() const {
QL_REQUIRE(arguments_.exercise->type() == Exercise::American,
"not an American Option");
boost::shared_ptr<AmericanExercise> ex =
boost::dynamic_pointer_cast<AmericanExercise>(arguments_.exercise);
QL_REQUIRE(ex, "non-American exercise given");
QL_REQUIRE(!ex->payoffAtExpiry(),
"payoff at expiry not handled");
boost::shared_ptr<StrikedTypePayoff> payoff =
boost::dynamic_pointer_cast<StrikedTypePayoff>(arguments_.payoff);
QL_REQUIRE(payoff, "non-striked payoff given");
Real variance = process_->blackVolatility()->blackVariance(
ex->lastDate(), payoff->strike());
DiscountFactor dividendDiscount = process_->dividendYield()->discount(
ex->lastDate());
DiscountFactor riskFreeDiscount = process_->riskFreeRate()->discount(
ex->lastDate());
Real spot = process_->stateVariable()->value();
QL_REQUIRE(spot > 0.0, "negative or null underlying given");
Real forwardPrice = spot * dividendDiscount / riskFreeDiscount;
BlackCalculator black(payoff, forwardPrice,
std::sqrt(variance), riskFreeDiscount);
if (dividendDiscount>=1.0 && payoff->optionType()==Option::Call) {
// early exercise never optimal
results_.value = black.value();
results_.delta = black.delta(spot);
results_.deltaForward = black.deltaForward();
results_.elasticity = black.elasticity(spot);
results_.gamma = black.gamma(spot);
DayCounter rfdc = process_->riskFreeRate()->dayCounter();
DayCounter divdc = process_->dividendYield()->dayCounter();
DayCounter voldc = process_->blackVolatility()->dayCounter();
Time t =
rfdc.yearFraction(process_->riskFreeRate()->referenceDate(),
arguments_.exercise->lastDate());
results_.rho = black.rho(t);
t = divdc.yearFraction(process_->dividendYield()->referenceDate(),
arguments_.exercise->lastDate());
results_.dividendRho = black.dividendRho(t);
t = voldc.yearFraction(process_->blackVolatility()->referenceDate(),
arguments_.exercise->lastDate());
results_.vega = black.vega(t);
results_.theta = black.theta(spot, t);
results_.thetaPerDay = black.thetaPerDay(spot, t);
results_.strikeSensitivity = black.strikeSensitivity();
results_.itmCashProbability = black.itmCashProbability();
} else {
// early exercise can be optimal
CumulativeNormalDistribution cumNormalDist;
NormalDistribution normalDist;
Real tolerance = 1e-6;
Real Sk = BaroneAdesiWhaleyApproximationEngine::criticalPrice(
payoff, riskFreeDiscount, dividendDiscount, variance,
tolerance);
Real forwardSk = Sk * dividendDiscount / riskFreeDiscount;
Real alpha = -2.0*std::log(riskFreeDiscount)/(variance);
Real beta = 2.0*std::log(dividendDiscount/riskFreeDiscount)/
(variance);
Real h = 1 - riskFreeDiscount;
Real phi;
switch (payoff->optionType()) {
case Option::Call:
phi = 1;
break;
case Option::Put:
phi = -1;
break;
default:
QL_FAIL("unknown option type");
}
//it can throw: to be fixed
// FLOATING_POINT_EXCEPTION
Real temp_root = std::sqrt ((beta-1)*(beta-1) + (4*alpha)/h);
Real lambda = (-(beta-1) + phi * temp_root) / 2;
Real lambda_prime = - phi * alpha / (h*h * temp_root);
Real black_Sk = blackFormula(payoff->optionType(), payoff->strike(),
forwardSk, std::sqrt(variance)) * riskFreeDiscount;
Real hA = phi * (Sk - payoff->strike()) - black_Sk;
Real d1_Sk = (std::log(forwardSk/payoff->strike()) + 0.5*variance)
/std::sqrt(variance);
Real d2_Sk = d1_Sk - std::sqrt(variance);
Real part1 = forwardSk * normalDist(d1_Sk) /
(alpha * std::sqrt(variance));
Real part2 = - phi * forwardSk * cumNormalDist(phi * d1_Sk) *
std::log(dividendDiscount) / std::log(riskFreeDiscount);
Real part3 = + phi * payoff->strike() * cumNormalDist(phi * d2_Sk);
Real V_E_h = part1 + part2 + part3;
Real b = (1-h) * alpha * lambda_prime / (2*(2*lambda + beta - 1));
Real c = - ((1 - h) * alpha / (2 * lambda + beta - 1)) *
(V_E_h / (hA) + 1 / h + lambda_prime / (2*lambda + beta - 1));
Real temp_spot_ratio = std::log(spot / Sk);
Real chi = temp_spot_ratio * (b * temp_spot_ratio + c);
if (phi*(Sk-spot) > 0) {
results_.value = black.value() +
hA * std::pow((spot/Sk), lambda) / (1 - chi);
} else {
results_.value = phi * (spot - payoff->strike());
}
Real temp_chi_prime = (2 * b / spot) * std::log(spot/Sk);
Real chi_prime = temp_chi_prime + c / spot;
Real chi_double_prime = 2*b/(spot*spot)
- temp_chi_prime / spot
- c / (spot*spot);
results_.delta = phi * dividendDiscount * cumNormalDist (phi * d1_Sk)
+ (lambda / (spot * (1 - chi)) + chi_prime / ((1 - chi)*(1 - chi))) *
(phi * (Sk - payoff->strike()) - black_Sk) * std::pow((spot/Sk), lambda);
results_.gamma = phi * dividendDiscount * normalDist (phi*d1_Sk) /
(spot * std::sqrt(variance))
+ (2 * lambda * chi_prime / (spot * (1 - chi) * (1 - chi))
+ 2 * chi_prime * chi_prime / ((1 - chi) * (1 - chi) * (1 - chi))
+ chi_double_prime / ((1 - chi) * (1 - chi))
+ lambda * (1 - lambda) / (spot * spot * (1 - chi)))
* (phi * (Sk - payoff->strike()) - black_Sk)
* std::pow((spot/Sk), lambda);
} // end of "early exercise can be optimal"
}
void BlackCapFloorEngine::calculate() const {
Real value = 0.0;
Real vega = 0.0;
Size optionlets = arguments_.startDates.size();
std::vector<Real> values(optionlets, 0.0);
std::vector<Real> vegas(optionlets, 0.0);
std::vector<Real> stdDevs(optionlets, 0.0);
CapFloor::Type type = arguments_.type;
Date today = vol_->referenceDate();
Date settlement = discountCurve_->referenceDate();
for (Size i=0; i<optionlets; ++i) {
Date paymentDate = arguments_.endDates[i];
// handling of settlementDate, npvDate and includeSettlementFlows
// should be implemented.
// For the time being just discard expired caplets
if (paymentDate > settlement) {
DiscountFactor d = arguments_.nominals[i] *
arguments_.gearings[i] *
discountCurve_->discount(paymentDate) *
arguments_.accrualTimes[i];
Rate forward = arguments_.forwards[i];
Date fixingDate = arguments_.fixingDates[i];
Time sqrtTime = 0.0;
if (fixingDate > today)
sqrtTime = std::sqrt(vol_->timeFromReference(fixingDate));
if (type == CapFloor::Cap || type == CapFloor::Collar) {
Rate strike = arguments_.capRates[i];
if (sqrtTime>0.0) {
stdDevs[i] = std::sqrt(vol_->blackVariance(fixingDate,
strike));
vegas[i] = blackFormulaStdDevDerivative(strike,
forward, stdDevs[i], d, displacement_) * sqrtTime;
}
// include caplets with past fixing date
values[i] = blackFormula(Option::Call,
strike, forward, stdDevs[i], d, displacement_);
}
if (type == CapFloor::Floor || type == CapFloor::Collar) {
Rate strike = arguments_.floorRates[i];
Real floorletVega = 0.0;
if (sqrtTime>0.0) {
stdDevs[i] = std::sqrt(vol_->blackVariance(fixingDate,
strike));
floorletVega = blackFormulaStdDevDerivative(strike,
forward, stdDevs[i], d, displacement_) * sqrtTime;
}
Real floorlet = blackFormula(Option::Put,
strike, forward, stdDevs[i], d, displacement_);
if (type == CapFloor::Floor) {
values[i] = floorlet;
vegas[i] = floorletVega;
} else {
// a collar is long a cap and short a floor
values[i] -= floorlet;
vegas[i] -= floorletVega;
}
}
value += values[i];
vega += vegas[i];
}
}
results_.value = value;
results_.additionalResults["vega"] = vega;
results_.additionalResults["optionletsPrice"] = values;
results_.additionalResults["optionletsVega"] = vegas;
results_.additionalResults["optionletsAtmForward"] = arguments_.forwards;
if (type != CapFloor::Collar)
results_.additionalResults["optionletsStdDev"] = stdDevs;
}
void KahaleSmileSection::compute() {
std::pair<Size,Size> afIdx = ssutils_->arbitragefreeIndices();
leftIndex_ = afIdx.first;
rightIndex_ = afIdx.second;
if(deleteArbitragePoints_) {
while(leftIndex_>1 || rightIndex_<k_.size()-1) {
ssutils_ = boost::shared_ptr<SmileSectionUtils>(new SmileSectionUtils(*source_,moneynessGrid_,f_));
std::pair<Size,Size> afIdx = ssutils_->arbitragefreeIndices();
leftIndex_ = afIdx.first;
rightIndex_ = afIdx.second;
QL_REQUIRE(rightIndex_>leftIndex_,
"arbitrage free region must at least contain two points (only index is " << leftIndex_ << ")");
if(leftIndex_>1) {
moneynessGrid_.erase(moneynessGrid_.begin()+leftIndex_-1);
k_.erase(k_.begin()+leftIndex_-1);
c_.erase(c_.begin()+leftIndex_-1);
leftIndex_--;
rightIndex_--;
}
if(rightIndex_<k_.size()-1) {
moneynessGrid_.erase(moneynessGrid_.begin()+rightIndex_+1);
k_.erase(k_.begin()+rightIndex_+1);
c_.erase(c_.begin()+rightIndex_+1);
rightIndex_--;
}
}
}
cFunctions_ = std::vector<boost::shared_ptr<cFunction> >(rightIndex_-leftIndex_+2);
// extrapolation in the leftmost interval
Brent brent;
bool success;
Real secl = 0.0;
do {
success=true;
try {
Real k1 = k_[leftIndex_];
Real c1 = c_[leftIndex_];
Real c0 = c_[0];
secl = (c_[leftIndex_]-c_[0]) / (k_[leftIndex_]-k_[0]);
Real sec = (c_[leftIndex_+1]-c_[leftIndex_]) / (k_[leftIndex_+1]-k_[leftIndex_]);
Real c1p;
if(interpolate_) c1p=(secl+sec)/2;
else {
c1p=(blackFormula(Option::Call, k1+gap_, f_, sqrt(source_->variance(k1+gap_)))-
blackFormula(Option::Call, k1, f_, sqrt(source_->variance(k1))))/gap_;
QL_REQUIRE(secl < c1p && c1p <= 0.0,"dummy");
// can not extrapolate so throw exception which is caught below
}
sHelper1 sh1(k1,c0,c1,c1p);
Real s = brent.solve(sh1,QL_KAHALE_ACC,0.20,0.00,QL_KAHALE_SMAX); // numerical parameters hardcoded here
sh1(s);
boost::shared_ptr<cFunction> cFct1(new cFunction(sh1.f_,s,0.0,sh1.b_));
cFunctions_[0]=cFct1;
} catch(...) {
leftIndex_++;
success=false;
}
} while(!success && leftIndex_ < rightIndex_);
QL_REQUIRE(leftIndex_ < rightIndex_, "can not extrapolate to left, right index of af region reached ("
<< rightIndex_ << ")");
// interpolation
Real cp0 = 0.0, cp1 = 0.0;
if(interpolate_) {
for(Size i = leftIndex_; i<rightIndex_; i++) {
Real k0 = k_[i];
Real k1 = k_[i+1];
Real c0 = c_[i];
Real c1 = c_[i+1];
Real sec = (c_[i+1]-c_[i]) / (k_[i+1]-k_[i]);
if(i==leftIndex_) cp0 = leftIndex_ > 0 ? (secl + sec) / 2.0 : sec;
Real secr;
if(i==rightIndex_-1) secr=0.0;
else secr = (c_[i+2]-c_[i+1]) / (k_[i+2]-k_[i+1]);
cp1 = (sec+secr) / 2.0;
aHelper ah(k0,k1,c0,c1,cp0,cp1);
Real a;
try {
a = brent.solve(ah,QL_KAHALE_ACC,0.5*(cp1+(1.0+cp0)),cp1+QL_KAHALE_EPS,1.0+cp0-QL_KAHALE_EPS);
// numerical parameters hardcoded here
} catch(...) {
// from theory there must exist a zero. if the solver does not find it, it most
// probably lies close one of the interval bounds. Just choose the better bound
// and relax the accuracy. This does not matter in practice usually.
Real la = std::fabs(ah(cp1+QL_KAHALE_EPS));
Real ra = std::fabs(ah(1.0+cp0-QL_KAHALE_EPS));
if( la < QL_KAHALE_ACC_RELAX || ra < QL_KAHALE_ACC_RELAX) { // tolerance hardcoded here
a = la < ra ? cp1+QL_KAHALE_EPS : 1.0+cp0-QL_KAHALE_EPS;
}
else
QL_FAIL("can not interpolate at index " << i);
}
ah(a);
boost::shared_ptr<cFunction> cFct(new cFunction(ah.f_,ah.s_,a,ah.b_));
cFunctions_[leftIndex_ > 0 ? i-leftIndex_+1 : 0]=cFct;
cp0=cp1;
}
}
// extrapolation of right wing
do {
success=true;
try {
Real k0 = k_[rightIndex_];
Real c0 = c_[rightIndex_];
Real cp0;
if(interpolate_) cp0 = 0.5*(c_[rightIndex_]-c_[rightIndex_-1])/(k_[rightIndex_]-k_[rightIndex_-1]);
else {
cp0=(blackFormula(Option::Call, k0, f_, sqrt(source_->variance(k0)))-
blackFormula(Option::Call, k0-gap_, f_, sqrt(source_->variance(k0-gap_))))/gap_;
}
boost::shared_ptr<cFunction> cFct;
if(exponentialExtrapolation_) {
cFct = boost::shared_ptr<cFunction>(new cFunction(-cp0/c0 ,std::log(c0)-cp0/c0*k0));
}
else {
sHelper sh(k0,c0,cp0);
Real s;
s = brent.solve(sh,QL_KAHALE_ACC,0.20,0.0,QL_KAHALE_SMAX); // numerical parameters hardcoded here
sh(s);
cFct = boost::shared_ptr<cFunction>(new cFunction(sh.f_,s,0.0,0.0));
}
cFunctions_[rightIndex_-leftIndex_+1]=cFct;
} catch (...) {
rightIndex_--;
success=false;
}
} while(!success && rightIndex_ > leftIndex_);
QL_REQUIRE(leftIndex_ < rightIndex_, "can not extrapolate to right, left index of af region reached (" <<
leftIndex_ << ")");
}
void BlackSwaptionEngine::calculate() const {
static const Spread basisPoint = 1.0e-4;
Date exerciseDate = arguments_.exercise->date(0);
// the part of the swap preceding exerciseDate should be truncated
// to avoid taking into account unwanted cashflows
VanillaSwap swap = *arguments_.swap;
Rate strike = swap.fixedRate();
// using the discounting curve
// swap.iborIndex() might be using a different forwarding curve
swap.setPricingEngine(boost::shared_ptr<PricingEngine>(new
DiscountingSwapEngine(discountCurve_, false)));
Rate atmForward = swap.fairRate();
// Volatilities are quoted for zero-spreaded swaps.
// Therefore, any spread on the floating leg must be removed
// with a corresponding correction on the fixed leg.
if (swap.spread()!=0.0) {
Spread correction = swap.spread() *
std::fabs(swap.floatingLegBPS()/swap.fixedLegBPS());
strike -= correction;
atmForward -= correction;
results_.additionalResults["spreadCorrection"] = correction;
} else {
results_.additionalResults["spreadCorrection"] = 0.0;
}
results_.additionalResults["strike"] = strike;
results_.additionalResults["atmForward"] = atmForward;
// using the discounting curve
swap.setPricingEngine(boost::shared_ptr<PricingEngine>(
new DiscountingSwapEngine(discountCurve_, false)));
Real annuity;
switch(arguments_.settlementType) {
case Settlement::Physical: {
annuity = std::fabs(swap.fixedLegBPS())/basisPoint;
break;
}
case Settlement::Cash: {
const Leg& fixedLeg = swap.fixedLeg();
boost::shared_ptr<FixedRateCoupon> firstCoupon =
boost::dynamic_pointer_cast<FixedRateCoupon>(fixedLeg[0]);
DayCounter dayCount = firstCoupon->dayCounter();
Real fixedLegCashBPS =
CashFlows::bps(fixedLeg,
InterestRate(atmForward, dayCount, Compounded, Annual),
false, discountCurve_->referenceDate()) ;
annuity = std::fabs(fixedLegCashBPS/basisPoint);
break;
}
default:
QL_FAIL("unknown settlement type");
}
results_.additionalResults["annuity"] = annuity;
// the swap length calculation might be improved using the value date
// of the exercise date
Time swapLength = vol_->swapLength(exerciseDate,
arguments_.floatingPayDates.back());
results_.additionalResults["swapLength"] = swapLength;
Real variance = vol_->blackVariance(exerciseDate,
swapLength,
strike);
Real stdDev = std::sqrt(variance);
results_.additionalResults["stdDev"] = stdDev;
Option::Type w = (arguments_.type==VanillaSwap::Payer) ?
Option::Call : Option::Put;
results_.value = blackFormula(w, strike, atmForward, stdDev, annuity,
displacement_);
Time exerciseTime = vol_->timeFromReference(exerciseDate);
results_.additionalResults["vega"] = std::sqrt(exerciseTime) *
blackFormulaStdDevDerivative(strike, atmForward, stdDev, annuity,
displacement_);
}
void VannaVolgaDoubleBarrierEngine::calculate() const {
const Real sigmaShift_vega = 0.001;
const Real sigmaShift_volga = 0.0001;
const Real spotShift_delta = 0.0001 * spotFX_->value();
const Real sigmaShift_vanna = 0.0001;
Handle<Quote> x0Quote( //used for shift
boost::make_shared<SimpleQuote>(spotFX_->value()));
Handle<Quote> atmVolQuote( //used for shift
boost::make_shared<SimpleQuote>(atmVol_->value()));
boost::shared_ptr<BlackVolTermStructure> blackVolTS =
boost::make_shared<BlackConstantVol>(
Settings::instance().evaluationDate(),
NullCalendar(), atmVolQuote, Actual365Fixed());
boost::shared_ptr<BlackScholesMertonProcess> stochProcess =
boost::make_shared<BlackScholesMertonProcess>(
x0Quote,
foreignTS_,
domesticTS_,
Handle<BlackVolTermStructure>(blackVolTS));
boost::shared_ptr<PricingEngine> engineBS =
boost::make_shared<AnalyticDoubleBarrierEngine>(stochProcess,
series_);
BlackDeltaCalculator blackDeltaCalculatorAtm(
Option::Call, atmVol_->deltaType(), x0Quote->value(),
domesticTS_->discount(T_), foreignTS_->discount(T_),
atmVol_->value() * sqrt(T_));
Real atmStrike = blackDeltaCalculatorAtm.atmStrike(atmVol_->atmType());
Real call25Vol = vol25Call_->value();
Real put25Vol = vol25Put_->value();
BlackDeltaCalculator blackDeltaCalculatorPut25(
Option::Put, vol25Put_->deltaType(), x0Quote->value(),
domesticTS_->discount(T_), foreignTS_->discount(T_),
put25Vol * sqrt(T_));
Real put25Strike = blackDeltaCalculatorPut25.strikeFromDelta(-0.25);
BlackDeltaCalculator blackDeltaCalculatorCall25(
Option::Call, vol25Call_->deltaType(), x0Quote->value(),
domesticTS_->discount(T_), foreignTS_->discount(T_),
call25Vol * sqrt(T_));
Real call25Strike = blackDeltaCalculatorCall25.strikeFromDelta(0.25);
//here use vanna volga interpolated smile to price vanilla
std::vector<Real> strikes;
std::vector<Real> vols;
strikes.push_back(put25Strike);
vols.push_back(put25Vol);
strikes.push_back(atmStrike);
vols.push_back(atmVol_->value());
strikes.push_back(call25Strike);
vols.push_back(call25Vol);
VannaVolga vannaVolga(x0Quote->value(), foreignTS_->discount(T_), foreignTS_->discount(T_), T_);
Interpolation interpolation = vannaVolga.interpolate(strikes.begin(), strikes.end(), vols.begin());
interpolation.enableExtrapolation();
const boost::shared_ptr<StrikedTypePayoff> payoff =
boost::dynamic_pointer_cast<StrikedTypePayoff>(arguments_.payoff);
Real strikeVol = interpolation(payoff->strike());
//vannila option price
Real vanillaOption = blackFormula(payoff->optionType(), payoff->strike(),
x0Quote->value()* foreignTS_->discount(T_)/ domesticTS_->discount(T_),
strikeVol * sqrt(T_),
domesticTS_->discount(T_));
//already out
if((x0Quote->value() > arguments_.barrier[1] || x0Quote->value() < arguments_.barrier[0])
&& arguments_.barrierType[0] == Barrier::DownOut) {
results_.value = 0.0;
results_.additionalResults["VanillaPrice"] = adaptVanDelta_? bsPriceWithSmile_ : vanillaOption;
results_.additionalResults["BarrierInPrice"] = adaptVanDelta_? bsPriceWithSmile_ : vanillaOption;
results_.additionalResults["BarrierOutPrice"] = 0.0;
}
//already in
else if((x0Quote->value() > arguments_.barrier[1] || x0Quote->value() < arguments_.barrier[0])
&& arguments_.barrierType[0] == Barrier::DownIn) {
results_.value = adaptVanDelta_? bsPriceWithSmile_ : vanillaOption;
results_.additionalResults["VanillaPrice"] = adaptVanDelta_? bsPriceWithSmile_ : vanillaOption;
results_.additionalResults["BarrierInPrice"] = adaptVanDelta_? bsPriceWithSmile_ : vanillaOption;
results_.additionalResults["BarrierOutPrice"] = 0.0;
}
else {
//set up BS barrier option pricing
//only calculate out barrier option price
// in barrier price = vanilla - out barrier
boost::shared_ptr<StrikedTypePayoff> payoff
= boost::static_pointer_cast<StrikedTypePayoff> (arguments_.payoff);
DoubleBarrierOption doubleBarrierOption(arguments_.barrierType,
arguments_.barrier,
arguments_.rebate,
payoff,
arguments_.exercise);
doubleBarrierOption.setPricingEngine(engineBS);
//BS price
Real priceBS = doubleBarrierOption.NPV();
Real priceAtmCallBS = blackFormula(Option::Call,atmStrike,
x0Quote->value()* foreignTS_->discount(T_)/ domesticTS_->discount(T_),
atmVol_->value() * sqrt(T_),
domesticTS_->discount(T_));
Real price25CallBS = blackFormula(Option::Call,call25Strike,
x0Quote->value()* foreignTS_->discount(T_)/ domesticTS_->discount(T_),
atmVol_->value() * sqrt(T_),
domesticTS_->discount(T_));
Real price25PutBS = blackFormula(Option::Put,put25Strike,
x0Quote->value()* foreignTS_->discount(T_)/ domesticTS_->discount(T_),
atmVol_->value() * sqrt(T_),
domesticTS_->discount(T_));
//market price
Real priceAtmCallMkt = blackFormula(Option::Call,atmStrike,
x0Quote->value()* foreignTS_->discount(T_)/ domesticTS_->discount(T_),
atmVol_->value() * sqrt(T_),
domesticTS_->discount(T_));
Real price25CallMkt = blackFormula(Option::Call,call25Strike,
x0Quote->value()* foreignTS_->discount(T_)/ domesticTS_->discount(T_),
call25Vol * sqrt(T_),
domesticTS_->discount(T_));
Real price25PutMkt = blackFormula(Option::Put,put25Strike,
x0Quote->value()* foreignTS_->discount(T_)/ domesticTS_->discount(T_),
put25Vol * sqrt(T_),
domesticTS_->discount(T_));
//Analytical Black Scholes formula
NormalDistribution norm;
Real d1atm = (std::log(x0Quote->value()* foreignTS_->discount(T_)/ domesticTS_->discount(T_)/atmStrike)
+ 0.5*std::pow(atmVolQuote->value(),2.0) * T_)/(atmVolQuote->value() * sqrt(T_));
Real vegaAtm_Analytical = x0Quote->value() * norm(d1atm) * sqrt(T_) * foreignTS_->discount(T_);
Real vannaAtm_Analytical = vegaAtm_Analytical/x0Quote->value() *(1.0 - d1atm/(atmVolQuote->value()*sqrt(T_)));
Real volgaAtm_Analytical = vegaAtm_Analytical * d1atm * (d1atm - atmVolQuote->value() * sqrt(T_))/atmVolQuote->value();
Real d125call = (std::log(x0Quote->value()* foreignTS_->discount(T_)/ domesticTS_->discount(T_)/call25Strike)
+ 0.5*std::pow(atmVolQuote->value(),2.0) * T_)/(atmVolQuote->value() * sqrt(T_));
Real vega25Call_Analytical = x0Quote->value() * norm(d125call) * sqrt(T_) * foreignTS_->discount(T_);
Real vanna25Call_Analytical = vega25Call_Analytical/x0Quote->value() *(1.0 - d125call/(atmVolQuote->value()*sqrt(T_)));
Real volga25Call_Analytical = vega25Call_Analytical * d125call * (d125call - atmVolQuote->value() * sqrt(T_))/atmVolQuote->value();
Real d125Put = (std::log(x0Quote->value()* foreignTS_->discount(T_)/ domesticTS_->discount(T_)/put25Strike)
+ 0.5*std::pow(atmVolQuote->value(),2.0) * T_)/(atmVolQuote->value() * sqrt(T_));
Real vega25Put_Analytical = x0Quote->value() * norm(d125Put) * sqrt(T_) * foreignTS_->discount(T_);
Real vanna25Put_Analytical = vega25Put_Analytical/x0Quote->value() *(1.0 - d125Put/(atmVolQuote->value()*sqrt(T_)));
Real volga25Put_Analytical = vega25Put_Analytical * d125Put * (d125Put - atmVolQuote->value() * sqrt(T_))/atmVolQuote->value();
//BS vega
boost::static_pointer_cast<SimpleQuote> (atmVolQuote.currentLink())->setValue(atmVolQuote->value() + sigmaShift_vega);
doubleBarrierOption.recalculate();
Real vegaBarBS = (doubleBarrierOption.NPV() - priceBS)/sigmaShift_vega;
boost::static_pointer_cast<SimpleQuote> (atmVolQuote.currentLink())->setValue(atmVolQuote->value() - sigmaShift_vega);//setback
//BS volga
//vegaBar2
//base NPV
boost::static_pointer_cast<SimpleQuote> (atmVolQuote.currentLink())->setValue(atmVolQuote->value() + sigmaShift_volga);
doubleBarrierOption.recalculate();
Real priceBS2 = doubleBarrierOption.NPV();
//shifted npv
boost::static_pointer_cast<SimpleQuote> (atmVolQuote.currentLink())->setValue(atmVolQuote->value() + sigmaShift_vega);
doubleBarrierOption.recalculate();
Real vegaBarBS2 = (doubleBarrierOption.NPV() - priceBS2)/sigmaShift_vega;
Real volgaBarBS = (vegaBarBS2 - vegaBarBS)/sigmaShift_volga;
boost::static_pointer_cast<SimpleQuote> (atmVolQuote.currentLink())->setValue(atmVolQuote->value()
- sigmaShift_volga
- sigmaShift_vega);//setback
//BS Delta
//base delta
boost::static_pointer_cast<SimpleQuote> (x0Quote.currentLink())->setValue(x0Quote->value() + spotShift_delta);//shift forth
doubleBarrierOption.recalculate();
Real priceBS_delta1 = doubleBarrierOption.NPV();
boost::static_pointer_cast<SimpleQuote> (x0Quote.currentLink())->setValue(x0Quote->value() - 2 * spotShift_delta);//shift back
doubleBarrierOption.recalculate();
Real priceBS_delta2 = doubleBarrierOption.NPV();
boost::static_pointer_cast<SimpleQuote> (x0Quote.currentLink())->setValue(x0Quote->value() + spotShift_delta);//set back
Real deltaBar1 = (priceBS_delta1 - priceBS_delta2)/(2.0*spotShift_delta);
//shifted vanna
boost::static_pointer_cast<SimpleQuote> (atmVolQuote.currentLink())->setValue(atmVolQuote->value() + sigmaShift_vanna);//shift sigma
//shifted delta
boost::static_pointer_cast<SimpleQuote> (x0Quote.currentLink())->setValue(x0Quote->value() + spotShift_delta);//shift forth
doubleBarrierOption.recalculate();
priceBS_delta1 = doubleBarrierOption.NPV();
boost::static_pointer_cast<SimpleQuote> (x0Quote.currentLink())->setValue(x0Quote->value() - 2 * spotShift_delta);//shift back
doubleBarrierOption.recalculate();
priceBS_delta2 = doubleBarrierOption.NPV();
boost::static_pointer_cast<SimpleQuote> (x0Quote.currentLink())->setValue(x0Quote->value() + spotShift_delta);//set back
Real deltaBar2 = (priceBS_delta1 - priceBS_delta2)/(2.0*spotShift_delta);
Real vannaBarBS = (deltaBar2 - deltaBar1)/sigmaShift_vanna;
boost::static_pointer_cast<SimpleQuote> (atmVolQuote.currentLink())->setValue(atmVolQuote->value() - sigmaShift_vanna);//set back
//Matrix
Matrix A(3,3,0.0);
//analytical
A[0][0] = vegaAtm_Analytical;
A[0][1] = vega25Call_Analytical;
A[0][2] = vega25Put_Analytical;
A[1][0] = vannaAtm_Analytical;
A[1][1] = vanna25Call_Analytical;
A[1][2] = vanna25Put_Analytical;
A[2][0] = volgaAtm_Analytical;
A[2][1] = volga25Call_Analytical;
A[2][2] = volga25Put_Analytical;
Array b(3,0.0);
b[0] = vegaBarBS;
b[1] = vannaBarBS;
b[2] = volgaBarBS;
Array q = inverse(A) * b;
Real H = arguments_.barrier[1];
Real L = arguments_.barrier[0];
Real theta_tilt_minus = ((domesticTS_->zeroRate(T_, Continuous) - foreignTS_->zeroRate(T_, Continuous))/atmVol_->value() - atmVol_->value()/2.0)*std::sqrt(T_);
Real h = 1.0/atmVol_->value() * std::log(H/x0Quote->value())/std::sqrt(T_);
Real l = 1.0/atmVol_->value() * std::log(L/x0Quote->value())/std::sqrt(T_);
CumulativeNormalDistribution cnd;
Real doubleNoTouch = 0.0;
for(int j = -series_; j< series_; j++ ) {
Real e_minus = 2*j*(h-l) - theta_tilt_minus;
doubleNoTouch += std::exp(-2.0*j*theta_tilt_minus*(h-l))*(cnd(h+e_minus) - cnd(l+e_minus))
- std::exp(-2.0*j*theta_tilt_minus*(h-l)+2.0*theta_tilt_minus*h)*(cnd(h-2.0*h+e_minus) - cnd(l-2.0*h+e_minus));
}
Real p_survival = doubleNoTouch;
Real lambda = p_survival ;
Real adjust = q[0]*(priceAtmCallMkt - priceAtmCallBS)
+ q[1]*(price25CallMkt - price25CallBS)
+ q[2]*(price25PutMkt - price25PutBS);
Real outPrice = priceBS + lambda*adjust;//
Real inPrice;
//adapt Vanilla delta
if(adaptVanDelta_ == true) {
outPrice += lambda*(bsPriceWithSmile_ - vanillaOption);
//capfloored by (0, vanilla)
outPrice = std::max(0.0, std::min(bsPriceWithSmile_, outPrice));
inPrice = bsPriceWithSmile_ - outPrice;
}
else {
//capfloored by (0, vanilla)
outPrice = std::max(0.0, std::min(vanillaOption , outPrice));
inPrice = vanillaOption - outPrice;
}
if(arguments_.barrierType[0] == Barrier::DownOut)
results_.value = outPrice;
else
results_.value = inPrice;
results_.additionalResults["VanillaPrice"] = vanillaOption;
results_.additionalResults["BarrierInPrice"] = inPrice;
results_.additionalResults["BarrierOutPrice"] = outPrice;
results_.additionalResults["lambda"] = lambda;
}
}
void KahaleSmileSection::compute() {
std::pair<Size, Size> afIdx = ssutils_->arbitragefreeIndices();
leftIndex_ = afIdx.first;
rightIndex_ = afIdx.second;
cFunctions_ = std::vector<boost::shared_ptr<cFunction> >(
rightIndex_ - leftIndex_ + 2);
// extrapolation in the leftmost interval
Brent brent;
bool success;
Real secl = 0.0;
do {
success = true;
try {
Real k1 = k_[leftIndex_];
Real c1 = c_[leftIndex_];
Real c0 = c_[0];
secl = (c_[leftIndex_] - c_[0]) / (k_[leftIndex_] - k_[0]);
Real sec = (c_[leftIndex_ + 1] - c_[leftIndex_]) /
(k_[leftIndex_ + 1] - k_[leftIndex_]);
Real c1p;
if (interpolate_)
c1p = (secl + sec) / 2;
else {
c1p = (blackFormula(Option::Call, k1 + gap_, f_,
sqrt(source_->variance(k1 + gap_))) -
blackFormula(Option::Call, k1, f_,
sqrt(source_->variance(k1)))) /
gap_;
QL_REQUIRE(secl < c1p && c1p <= 0.0, "dummy");
// can not extrapolate so throw exception which is caught
// below
}
sHelper1 sh1(k1, c0, c1, c1p);
Real s = brent.solve(sh1, QL_KAHALE_ACC, 0.20, 0.00,
QL_KAHALE_SMAX); // numerical parameters
// hardcoded here
sh1(s);
boost::shared_ptr<cFunction> cFct1(
new cFunction(sh1.f_, s, 0.0, sh1.b_));
cFunctions_[0] = cFct1;
// sanity check - in rare cases we can get digitials
// which are not monotonic or greater than 1.0
// due to numerical effects. Move to the next index in
// these cases.
Real dig = digitalOptionPrice(k1 / 2.0);
QL_REQUIRE(dig >= -c1p && dig <= 1.0, "dummy");
}
catch (...) {
leftIndex_++;
success = false;
}
} while (!success && leftIndex_ < rightIndex_);
QL_REQUIRE(
leftIndex_ < rightIndex_,
"can not extrapolate to left, right index of af region reached ("
<< rightIndex_ << ")");
// interpolation
Real cp0 = 0.0, cp1 = 0.0;
if (interpolate_) {
for (Size i = leftIndex_; i < rightIndex_; i++) {
Real k0 = k_[i];
Real k1 = k_[i + 1];
Real c0 = c_[i];
Real c1 = c_[i + 1];
Real sec = (c_[i + 1] - c_[i]) / (k_[i + 1] - k_[i]);
if (i == leftIndex_)
cp0 = leftIndex_ > 0 ? (secl + sec) / 2.0 : sec;
Real secr;
if (i == rightIndex_ - 1)
secr = 0.0;
else
secr = (c_[i + 2] - c_[i + 1]) / (k_[i + 2] - k_[i + 1]);
cp1 = (sec + secr) / 2.0;
aHelper ah(k0, k1, c0, c1, cp0, cp1);
Real a;
bool valid = false;
try {
a = brent.solve(
ah, QL_KAHALE_ACC, 0.5 * (cp1 + (1.0 + cp0)),
cp1 + QL_KAHALE_EPS, 1.0 + cp0 - QL_KAHALE_EPS);
// numerical parameters hardcoded here
valid = true;
}
catch (...) {
// delete the right point of the interval where we try to
// interpolate
moneynessGrid_.erase(moneynessGrid_.begin() + (i + 1));
k_.erase(k_.begin() + (i + 1));
c_.erase(c_.begin() + (i + 1));
cFunctions_.erase(cFunctions_.begin() + (i + 1));
rightIndex_--;
i--;
}
if (valid) {
ah(a);
boost::shared_ptr<cFunction> cFct(
new cFunction(ah.f_, ah.s_, a, ah.b_));
cFunctions_[leftIndex_ > 0 ? i - leftIndex_ + 1 : 0] = cFct;
cp0 = cp1;
}
}
}
// extrapolation of right wing
do {
success = true;
try {
Real k0 = k_[rightIndex_];
Real c0 = c_[rightIndex_];
Real cp0;
if (interpolate_)
cp0 = 0.5 * (c_[rightIndex_] - c_[rightIndex_ - 1]) /
(k_[rightIndex_] - k_[rightIndex_ - 1]);
else {
cp0 = (blackFormula(Option::Call, k0, f_,
sqrt(source_->variance(k0))) -
blackFormula(Option::Call, k0 - gap_, f_,
sqrt(source_->variance(k0 - gap_)))) /
gap_;
}
boost::shared_ptr<cFunction> cFct;
if (exponentialExtrapolation_) {
QL_REQUIRE(-cp0 / c0 > 0.0, "dummy"); // this is caught
// below
cFct = boost::shared_ptr<cFunction>(
new cFunction(-cp0 / c0, std::log(c0) - cp0 / c0 * k0));
} else {
sHelper sh(k0, c0, cp0);
Real s;
s = brent.solve(sh, QL_KAHALE_ACC, 0.20, 0.0,
QL_KAHALE_SMAX); // numerical parameters
// hardcoded here
sh(s);
cFct = boost::shared_ptr<cFunction>(
new cFunction(sh.f_, s, 0.0, 0.0));
}
cFunctions_[rightIndex_ - leftIndex_ + 1] = cFct;
}
catch (...) {
rightIndex_--;
success = false;
}
} while (!success && rightIndex_ > leftIndex_);
QL_REQUIRE(
leftIndex_ < rightIndex_,
"can not extrapolate to right, left index of af region reached ("
<< leftIndex_ << ")");
}