GJRGARCHProcess Class Reference
Stochastic processes

Stochastic-volatility GJR-GARCH(1,1) process. More...

`#include <ql/processes/gjrgarchprocess.hpp>`

Inheritance diagram for GJRGARCHProcess:
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## Public Types

enum | Discretization { PartialTruncation, FullTruncation, Reflection }
Public Types inherited from Observer
typedef std::set< boost::shared_ptr< Observable > > | set_type
typedef set_type::iterator | iterator

## Public Member Functions

| GJRGARCHProcess (const Handle< YieldTermStructure > &riskFreeRate, const Handle< YieldTermStructure > &dividendYield, const Handle< Quote > &s0, Real v0, Real omega, Real alpha, Real beta, Real gamma, Real lambda, Real daysPerYear=252.0, Discretization d=FullTruncation)
Size | size () const
| returns the number of dimensions of the stochastic process
Disposable< Array > | initialValues () const
| returns the initial values of the state variables
Disposable< Array > | drift (Time t, const Array &x) const
| returns the drift part of the equation, i.e., \( \mu(t, \mathrm{x}_t) \)
Disposable< Matrix > | diffusion (Time t, const Array &x) const
| returns the diffusion part of the equation, i.e. \( \sigma(t, \mathrm{x}_t) \)
Disposable< Array > | apply (const Array &x0, const Array &dx) const
Disposable< Array > | evolve (Time t0, const Array &x0, Time dt, const Array &dw) const
Real | v0 () const
Real | lambda () const
Real | omega () const
Real | alpha () const
Real | beta () const
Real | gamma () const
Real | daysPerYear () const
const Handle< Quote > & | s0 () const
const Handle< YieldTermStructure > & | dividendYield () const
const Handle< YieldTermStructure > & | riskFreeRate () const
Time | time (const Date &) const
Public Member Functions inherited from StochasticProcess
virtual Size | factors () const
| returns the number of independent factors of the process
virtual Disposable< Array > | expectation (Time t0, const Array &x0, Time dt) const
virtual Disposable< Matrix > | stdDeviation (Time t0, const Array &x0, Time dt) const
virtual Disposable< Matrix > | covariance (Time t0, const Array &x0, Time dt) const
void | update ()
Public Member Functions inherited from Observer
| Observer (const Observer &)
Observer & | operator= (const Observer &)
std::pair< iterator, bool > | registerWith (const boost::shared_ptr< Observable > &)
void | registerWithObservables (const boost::shared_ptr< Observer > &)
Size | unregisterWith (const boost::shared_ptr< Observable > &)
void | unregisterWithAll ()
virtual void | deepUpdate ()
Public Member Functions inherited from Observable
| Observable (const Observable &)
Observable & | operator= (const Observable &)
void | notifyObservers ()

## Additional Inherited Members

Protected Member Functions inherited from StochasticProcess
| StochasticProcess (const boost::shared_ptr< discretization > &)
Protected Attributes inherited from StochasticProcess
boost::shared_ptr< discretization > | discretization_

## Detailed Description

Stochastic-volatility GJR-GARCH(1,1) process.

This class describes the stochastic volatility process governed by

\[ \begin{array}{rcl} dS(t, S) &=& \mu S dt + \sqrt{v} S dW_1 \\ dv(t, S) &=& (\omega + (\beta + \alpha * q_{2} + \gamma * q_{3} - 1) v) dt + (\alpha \sigma_{12} + \gamma \sigma_{13}) v dW_1 + \sqrt{\alpha^{2} (\sigma^{2}_{2} - \sigma^{2}_{12}) + \gamma^{2} (\sigma^{2}_{3} - \sigma^{2}_{13}) + 2 \alpha \gamma (\sigma_{23} - \sigma_{12} \sigma_{13})} v dW_2 \ \ N = normalCDF(\lambda) \\ n &=& \exp{-\lambda^{2}/2} / \sqrt{2 \pi} \\ q_{2} &=& 1 + \lambda^{2} \\ q_{3} &=& \lambda n + N + \lambda^2 N \\ \sigma^{2}_{2} = 2 + 4 \lambda^{4} \\ \sigma^{2}_{3} = \lambda^{3} n + 5 \lambda n + 3N + \lambda^{4} N + 6 \lambda^{2} N -\\lambda^{2} n^{2} - N^{2} - \lambda^{4} N^{2} - 2 \lambda n N - 2 \lambda^{3} nN - 2 \lambda^{2} N^{2} \ \ \sigma_{12} = -2 \lambda \\ \sigma_{13} = -2 n - 2 \lambda N \\ \sigma_{23} = 2N + \sigma_{12} \sigma_{13} \\ \end{array} \]

## Member Function Documentation

## apply()

Disposable<Array> apply | ( | const Array & | x0,
|  | const Array & | dx
| ) |  | const

virtual

applies a change to the asset value. By default, it returns \( \mathrm{x} + \Delta \mathrm{x} \).

Reimplemented from StochasticProcess.

## evolve()

Disposable<Array> evolve | ( | Time | t0,
|  | const Array & | x0,
|  | Time | dt,
|  | const Array & | dw
| ) |  | const

virtual

returns the asset value after a time interval \( \Delta t \) according to the given discretization. By default, it returns

\[ E(\mathrm{x}_0,t_0,\Delta t) + S(\mathrm{x}_0,t_0,\Delta t) \cdot \Delta \mathrm{w} \]

where \( E \) is the expectation and \( S \) the standard deviation.

Reimplemented from StochasticProcess.

## time()

Time time | ( | const Date & |  | ) | const

virtual

returns the time value corresponding to the given date in the reference system of the stochastic process.

Note
  As a number of processes might not need this functionality, a default implementation is given which raises an exception.

Reimplemented from StochasticProcess.