CTA performance table energy dispersion class. More...

#include <GCTAEdispPerfTable.hpp>

Inheritance diagram for GCTAEdispPerfTable:

Public Member Functions
	GCTAEdispPerfTable (void)
	Void constructor. More...

	GCTAEdispPerfTable (const GFilename &filename)
	File constructor. More...

	GCTAEdispPerfTable (const GCTAEdispPerfTable &psf)
	Copy constructor. More...

virtual	~GCTAEdispPerfTable (void)
	Destructor. More...

GCTAEdispPerfTable &	operator= (const GCTAEdispPerfTable &psf)
	Assignment operator. More...

double	operator() (const GEnergy &ereco, const GEnergy &etrue, const double &theta=0.0, const double &phi=0.0, const double &zenith=0.0, const double &azimuth=0.0) const
	Return energy dispersion in units of MeV \(^{-1}\). More...

void	clear (void)
	Clear instance. More...

GCTAEdispPerfTable *	clone (void) const
	Clone instance. More...

std::string	classname (void) const
	Return class name. More...

void	load (const GFilename &filename)
	Load energy dispersion from performance table. More...

GFilename	filename (void) const
	Return filename. More...

GEnergy	mc (GRan &ran, const GEnergy &etrue, const double &theta=0.0, const double &phi=0.0, const double &zenith=0.0, const double &azimuth=0.0) const
	Simulate energy dispersion. More...

GEbounds	ereco_bounds (const GEnergy &etrue, const double &theta=0.0, const double &phi=0.0, const double &zenith=0.0, const double &azimuth=0.0) const
	Return observed energy interval that contains the energy dispersion. More...

GEbounds	etrue_bounds (const GEnergy &ereco, const double &theta=0.0, const double &phi=0.0, const double &zenith=0.0, const double &azimuth=0.0) const
	Return true energy interval that contains the energy dispersion. More...

double	prob_erecobin (const GEnergy &ereco_min, const GEnergy &ereco_max, const GEnergy &etrue, const double &theta) const
	Return energy dispersion probability for reconstructed energy interval. More...

std::string	print (const GChatter &chatter=NORMAL) const
	Print energy dispersion information. More...

Public Member Functions inherited from GCTAEdisp
	GCTAEdisp (void)
	Void constructor. More...

	GCTAEdisp (const GCTAEdisp &edisp)
	Copy constructor. More...

virtual	~GCTAEdisp (void)
	Destructor. More...

GCTAEdisp &	operator= (const GCTAEdisp &edisp)
	Assignment operator. More...

Public Member Functions inherited from GBase
virtual	~GBase (void)
	Destructor. More...

Private Member Functions
void	init_members (void)
	Initialise class members. More...

void	copy_members (const GCTAEdispPerfTable &psf)
	Copy class members. More...

void	free_members (void)
	Delete class members. More...

void	update (const double &logE) const
	Update energy dispersion parameter cache. More...

Private Attributes
GFilename	m_filename
	Name of response file. More...

GNodeArray	m_logE
	log(E) nodes for interpolation More...

std::vector< double >	m_sigma
	Sigma value (rms) of energy resolution. More...

double	m_par_logE
	Energy for which precomputation is done. More...

double	m_par_scale
	Gaussian normalization. More...

double	m_par_sigma
	Gaussian sigma. More...

double	m_par_width
	Gaussian width parameter. More...

Additional Inherited Members
Protected Member Functions inherited from GCTAEdisp
void	init_members (void)
	Initialise class members. More...

void	copy_members (const GCTAEdisp &edisp)
	Copy class members. More...

void	free_members (void)
	Delete class members. More...

Detailed Description

CTA performance table energy dispersion class.

This class implements the CTA energy dispersion response as function of true energy as determined from a performance table. A performance table is an ASCII file that represent a table, specifying the CTA performance parameters as function of true photon energy.

The energy dispersion is defined as

\[ E_{\rm disp}(E_{\rm true}, E_{\rm reco}) = \frac{1}{\sqrt{2\pi}\sigma(E_{\rm true})} \exp \left(\frac{-(\log_{10} E_{\rm reco} - \log_{10} E_{\rm true})^2} {2 \sigma(E_{\rm true})^2} \right) \times \frac{1}{\log_{10} E_{\rm reco}} \]

and given in units of MeV \(^{-1}\), where \(E_{\rm reco}\) is the reconstructed energy in units of MeV, \(E_{\rm true}\) is the true energy in units of MeV, and \(\sigma(E_{\rm true})\) is the standard deviation of the energy dispersion that depends on the true photon energy.

Definition at line 67 of file GCTAEdispPerfTable.hpp.

Constructor & Destructor Documentation

GCTAEdispPerfTable::GCTAEdispPerfTable ( void )

Void constructor.

Definition at line 60 of file GCTAEdispPerfTable.cpp.

References init_members().

Referenced by clone().

GCTAEdispPerfTable::GCTAEdispPerfTable ( const GFilename & filename )

explicit

File constructor.

Parameters

[in] filename Performance table file name.

Construct instance by loading the energy dispersion information from an ASCII performance table.

Definition at line 78 of file GCTAEdispPerfTable.cpp.

References init_members(), and load().

GCTAEdispPerfTable::GCTAEdispPerfTable ( const GCTAEdispPerfTable & edisp )

Copy constructor.

Parameters

[in] edisp Energy dispersion

Definition at line 97 of file GCTAEdispPerfTable.cpp.

References copy_members(), and init_members().

GCTAEdispPerfTable::~GCTAEdispPerfTable ( void )

virtual

Destructor.

Definition at line 114 of file GCTAEdispPerfTable.cpp.

References free_members().

Member Function Documentation

std::string GCTAEdispPerfTable::classname ( void ) const

inlinevirtual

Return class name.

Returns: String containing the class name ("GCTAEdispPerfTable").

Implements GCTAEdisp.

Definition at line 139 of file GCTAEdispPerfTable.hpp.

void GCTAEdispPerfTable::clear ( void )

virtual

Clear instance.

This method properly resets the object to an initial state.

Implements GCTAEdisp.

Definition at line 224 of file GCTAEdispPerfTable.cpp.

References GCTAEdisp::free_members(), free_members(), GCTAEdisp::init_members(), and init_members().

GCTAEdispPerfTable * GCTAEdispPerfTable::clone ( void ) const

virtual

Clone instance.

Returns: Deep copy of instance.

Implements GCTAEdisp.

Definition at line 244 of file GCTAEdispPerfTable.cpp.

References GCTAEdispPerfTable().

void GCTAEdispPerfTable::copy_members ( const GCTAEdispPerfTable & edisp )

private

Copy class members.

Parameters

[in] edisp Energy dispersion

Definition at line 562 of file GCTAEdispPerfTable.cpp.

References m_filename, m_logE, m_par_logE, m_par_scale, m_par_sigma, m_par_width, and m_sigma.

Referenced by GCTAEdispPerfTable(), and operator=().

GEbounds GCTAEdispPerfTable::ereco_bounds	(	const GEnergy &	etrue,
		const double &	theta = `0.0`,
		const double &	phi = `0.0`,
		const double &	zenith = `0.0`,
		const double &	azimuth = `0.0`
	)		const

virtual

Return observed energy interval that contains the energy dispersion.

Parameters

[in]	etrue	True photon energy.
[in]	theta	Offset angle in camera system (radians). Not used.
[in]	phi	Azimuth angle in camera system (radians). Not used.
[in]	zenith	Zenith angle in Earth system (radians). Not used.
[in]	azimuth	Azimuth angle in Earth system (radians). Not used.

Returns: Boundaries of reconstruced energies.

Returns the band of observed energies outside of which the energy dispersion becomes negligible for a given true energy logEsrc. This band is set to \(\pm 5 \times \sigma\), where \(\sigma\) is the Gaussian width of the energy dispersion.

Implements GCTAEdisp.

Definition at line 378 of file GCTAEdispPerfTable.cpp.

References GNodeArray::interpolate(), GEnergy::log10TeV(), m_logE, and m_sigma.

GEbounds GCTAEdispPerfTable::etrue_bounds	(	const GEnergy &	ereco,
		const double &	theta = `0.0`,
		const double &	phi = `0.0`,
		const double &	zenith = `0.0`,
		const double &	azimuth = `0.0`
	)		const

virtual

Return true energy interval that contains the energy dispersion.

Parameters

[in]	ereco	Reconstructed event energy.
[in]	theta	Offset angle in camera system (radians). Not used.
[in]	phi	Azimuth angle in camera system (radians). Not used.
[in]	zenith	Zenith angle in Earth system (radians). Not used.
[in]	azimuth	Azimuth angle in Earth system (radians). Not used.

Returns: Boundaries of true energies.

Returns the band of true photon energies outside of which the energy dispersion becomes negligible for a given observed energy logEobs. This band is set to \(\pm 5 \times \sigma\), where \(\sigma\) is the Gaussian width of the energy dispersion.

Implements GCTAEdisp.

Definition at line 419 of file GCTAEdispPerfTable.cpp.

References GNodeArray::interpolate(), GEnergy::log10TeV(), m_logE, and m_sigma.

GFilename GCTAEdispPerfTable::filename ( void ) const

inlinevirtual

Return filename.

Returns: Returns filename from which the energy resolution was loaded

Implements GCTAEdisp.

Definition at line 151 of file GCTAEdispPerfTable.hpp.

References m_filename.

Referenced by load().

void GCTAEdispPerfTable::free_members ( void )

private

Delete class members.

Definition at line 581 of file GCTAEdispPerfTable.cpp.

Referenced by clear(), operator=(), and ~GCTAEdispPerfTable().

void GCTAEdispPerfTable::init_members ( void )

private

Initialise class members.

Definition at line 541 of file GCTAEdispPerfTable.cpp.

References GNodeArray::clear(), GFilename::clear(), m_filename, m_logE, m_par_logE, m_par_scale, m_par_sigma, m_par_width, and m_sigma.

Referenced by clear(), GCTAEdispPerfTable(), and operator=().

void GCTAEdispPerfTable::load ( const GFilename & filename )

virtual

Load energy dispersion from performance table.

Parameters

[in] filename Performance table file name.

Exceptions

GException::file_error File could not be opened for read access.

This method loads the energy dispersion information from an ASCII performance table. The energy resolution is stored in the 5th column of the performance table as RMS(ln(Eest/Etrue)). The method converts this internally to a sigma value by multiplying the stored values by 1/ln(10).

Implements GCTAEdisp.

Definition at line 264 of file GCTAEdispPerfTable.cpp.

References GNodeArray::append(), GNodeArray::clear(), filename(), G_LOAD, gammalib::inv_ln10, m_filename, m_logE, m_sigma, gammalib::split(), gammalib::strip_whitespace(), gammalib::todouble(), and GFilename::url().

Referenced by GCTAEdispPerfTable().

GEnergy GCTAEdispPerfTable::mc	(	GRan &	ran,
		const GEnergy &	etrue,
		const double &	theta = `0.0`,
		const double &	phi = `0.0`,
		const double &	zenith = `0.0`,
		const double &	azimuth = `0.0`
	)		const

virtual

Simulate energy dispersion.

Parameters

[in]	ran	Random number generator.
[in]	etrue	True photon energy.
[in]	theta	Offset angle in camera system (radians). Not used.
[in]	phi	Azimuth angle in camera system (radians). Not used.
[in]	zenith	Zenith angle in Earth system (radians). Not used.
[in]	azimuth	Azimuth angle in Earth system (radians). Not used.

Returns: Energy.

Draws observed energy value from a normal distribution of width m_par_sigma around logE.

Implements GCTAEdisp.

Definition at line 338 of file GCTAEdispPerfTable.cpp.

References GEnergy::log10TeV(), m_par_sigma, GRan::normal(), and update().

double GCTAEdispPerfTable::operator()	(	const GEnergy &	ereco,
		const GEnergy &	etrue,
		const double &	theta = `0.0`,
		const double &	phi = `0.0`,
		const double &	zenith = `0.0`,
		const double &	azimuth = `0.0`
	)		const

virtual

Return energy dispersion in units of MeV \(^{-1}\).

Parameters

[in]	ereco	Reconstructed photon energy.
[in]	etrue	True photon energy.
[in]	theta	Offset angle in camera system (radians). Not used.
[in]	phi	Azimuth angle in camera system (radians). Not used.
[in]	zenith	Zenith angle in Earth system (radians). Not used.
[in]	azimuth	Azimuth angle in Earth system (radians). Not used.

Returns: Energy dispersion (MeV \(^{-1}\))

Returns the energy dispersion

\[ E_{\rm disp}(E_{\rm reco} | E_{\rm true}) = \frac{1}{\sqrt{2\pi}\sigma(E_{\rm true})} \exp \left(\frac{-(\log_{10} E_{\rm reco} - \log_{10} E_{\rm true})^2} {2 \sigma(E_{\rm true})^2} \right) \times \frac{1}{\log_{10} E_{\rm reco}} \]

in units of MeV \(^{-1}\) where \(E_{\rm reco}\) is the reconstructed energy, \(E_{\rm true}\) is the true energy, and \(\sigma(E_{\rm true})\) is the standard deviation of the energy dispersion that depends on the true photon energy.

Implements GCTAEdisp.

Definition at line 187 of file GCTAEdispPerfTable.cpp.

References exp(), gammalib::ln10, GEnergy::log10TeV(), m_par_scale, m_par_width, GEnergy::MeV(), and update().

GCTAEdispPerfTable & GCTAEdispPerfTable::operator= ( const GCTAEdispPerfTable & edisp )

Assignment operator.

Parameters

[in] edisp Energy dispersion

Returns: Energy dispersion

Definition at line 136 of file GCTAEdispPerfTable.cpp.

References copy_members(), free_members(), init_members(), and GCTAEdisp::operator=().

std::string GCTAEdispPerfTable::print ( const GChatter & chatter = NORMAL ) const

virtual

Print energy dispersion information.

Parameters

[in] chatter Chattiness.

Returns: String containing energy dispersion information.

Implements GCTAEdisp.

Definition at line 492 of file GCTAEdispPerfTable.cpp.

References GNodeArray::append(), m_filename, m_logE, m_sigma, gammalib::parformat(), pow(), gammalib::reduce(), SILENT, GNodeArray::size(), and gammalib::str().

double GCTAEdispPerfTable::prob_erecobin	(	const GEnergy &	ereco_min,
		const GEnergy &	ereco_max,
		const GEnergy &	etrue,
		const double &	theta
	)		const

virtual

Return energy dispersion probability for reconstructed energy interval.

Parameters

[in]	ereco_min	Minimum of reconstructed energy interval.
[in]	ereco_max	Maximum of reconstructed energy interval.
[in]	etrue	True energy.
[in]	theta	Offset angle (radians). Not used.

Returns: Integrated energy dispersion probability.

Computes

\[ \int_{E_{\rm reco}^{\rm min}}^{E_{\rm reco}^{\rm max}} E_{\rm disp}(E_{\rm reco} | E_{\rm true}) \, dE_{\rm reco} \]

where \(E_{\rm reco}\) is the reconstructed energy and \(E_{\rm true}\) is the true energy.

Implements GCTAEdisp.

Definition at line 466 of file GCTAEdispPerfTable.cpp.

References gammalib::gauss_integral(), GEnergy::log10TeV(), m_par_sigma, and update().

void GCTAEdispPerfTable::update ( const double & logE ) const

private

Update energy dispersion parameter cache.

Parameters

[in] logE Log10 of the true photon energy ( \(\log_{10}\) TeV).

This method updates the energy dispersion parameter cache. As the performance table energy dispersion only depends on true photon energy, the only parameter on which the cache values depend is the true photon energy.

Definition at line 598 of file GCTAEdispPerfTable.cpp.

References GNodeArray::interpolate(), gammalib::inv_sqrt2pi, m_logE, m_par_logE, m_par_scale, m_par_sigma, m_par_width, and m_sigma.

Referenced by mc(), operator()(), and prob_erecobin().