the FastJet namespace More...

Namespaces
	gas
	namespace to hold default parameters for the active area spec

Classes
class	VoronoiAreaSpec
	Specification for the computation of the Voronoi jet area. More...

class	AreaDefinition
	class that holds a generic area definition More...

class	ClusterSequence
	deals with clustering More...

class	ClusterSequence1GhostPassiveArea
	Like ClusterSequence with computation of the passive jet area by adding a single ghost. More...

class	ClusterSequenceActiveArea
	Like ClusterSequence with computation of the active jet area. More...

class	ClusterSequenceActiveAreaExplicitGhosts
	Like ClusterSequence with computation of the active jet area with the addition of explicit ghosts. More...

class	ClusterSequenceArea
	General class for user to obtain ClusterSequence with additional area information. More...

class	ClusterSequenceAreaBase
	base class that sets interface for extensions of ClusterSequence that provide information about the area of each jet More...

class	ClusterSequencePassiveArea
	Like ClusterSequence with computation of the passive jet area. More...

class	ClusterSequenceStructure
	Contains any information related to the clustering that should be directly accessible to PseudoJet. More...

class	ClusterSequenceVoronoiArea
	Like ClusterSequence with computation of the Voronoi jet area. More...

class	CompositeJetStructure
	The structure for a jet made of pieces. More...

class	Error
	base class corresponding to errors that can be thrown by FastJet More...

class	InternalError
	class corresponding to critical internal errors More...

class	FunctionOfPseudoJet
	base class providing interface for a generic function of a PseudoJet More...

class	GhostedAreaSpec
	Parameters to configure the computation of jet areas using ghosts. More...

class	JetDefinition
	class that is intended to hold a full definition of the jet clusterer More...

class	LimitedWarning
	class to provide facilities for giving warnings up to some maximum number of times and to provide global summaries of warnings that have been issued. More...

class	_NoInfo
	internal dummy class, used as a default template argument More...

class	NNInfo
	internal helper template class to facilitate initialisation of a BJ with a PseudoJet and extra information. More...

class	NNInfo< _NoInfo >
	for cases where there is no extra info More...

class	NNBase
	Helps solve closest pair problems with generic interparticle and particle-beam distances. More...

class	NNFJN2Plain
	Helps solve closest pair problems with factorised interparticle and beam distances (ie satisfying the FastJet lemma) More...

class	NNFJN2Tiled
	Helps solve closest pair problems with factorised interparticle and beam distances (ie satisfying the FastJet lemma) that are on a cylindrical geometry and allow tiling. More...

class	NNH
	Help solve closest pair problems with generic interparticle and beam distance (generic case) More...

class	PseudoJet
	Class to contain pseudojets, including minimal information of use to jet-clustering routines. More...

class	PseudoJetStructureBase
	Contains any information related to the clustering that should be directly accessible to PseudoJet. More...

class	RangeDefinition
	class for holding a range definition specification, given by limits on rapidity and azimuth. More...

class	TilingBase
	Class to indicate generic structure of tilings. More...

class	RectangularGrid
	Class that holds a generic rectangular tiling. More...

class	SelectorWorker
	default selector worker is an abstract virtual base class More...

class	Selector
	Class that encodes information about cuts and other selection criteria that can be applied to PseudoJet(s). More...

class	SharedPtr
	An implementation of shared pointers that is broadly similar to C++11 shared_ptr (https://en.cppreference.com/w/cpp/memory/shared_ptr). More...

class	WrappedStructure
	This wraps a (shared) pointer to an underlying structure. More...

class	EtaPhi
	Shortcut for dealing with eta-phi coordinates. More...

class	TiledJet
	structure analogous to BriefJet, but with the extra information needed for dealing with tiles More...

class	TilingExtent
	class to perform a fast analysis of the appropriate rapidity range in which to perform tiling More...

class	BackgroundEstimate
	/// a class that holds the result of the calculation More...

class	BackgroundEstimatorBase
	Abstract base class that provides the basic interface for classes that estimate levels of background radiation in hadron and heavy-ion collider events. More...

class	BackgroundRescalingYPolynomial
	A background rescaling that is a simple polynomial in y. More...

class	Boost
	Class to boost a PseudoJet. More...

class	Unboost
	Class to un-boost a PseudoJet. More...

class	CASubJetTagger
	clean (almost parameter-free) tagger searching for the element in the clustering history that maximises a chosen distance More...

class	CASubJetTaggerStructure
	the structure returned by a CASubJetTagger More...

class	Filter
	Class that helps perform filtering (Butterworth, Davison, Rubin and Salam, arXiv:0802.2470) and trimming (Krohn, Thaler and Wang, arXiv:0912.1342) on jets, optionally in conjunction with subtraction (Cacciari and Salam, arXiv:0707.1378). More...

class	FilterStructure
	Class to contain structure information for a filtered jet. More...

class	GridMedianBackgroundEstimator
	Background Estimator based on the median pt/area of a set of grid cells. More...

class	JetMedianBackgroundEstimator
	Class to estimate the pt density of the background per unit area, using the median of the distribution of pt/area from jets that pass some selection criterion. More...

class	BackgroundJetPtDensity
	Class that implements pt/area_4vector.perp() for background estimation (this is a preliminary class). More...

class	BackgroundJetScalarPtDensity
	Class that implements (scalar pt sum of jet)/(scalar area of jet) for background estimation (this is a preliminary class). More...

class	BackgroundJetPtMDensity
	Class that implements $\frac{1}{A} \sum_{i \in jet} (\sqrt{p_{ti}^2+m^2} - p_{ti})$ for background estimation (this is a preliminary class). More...

class	JHTopTagger
	Class that helps perform boosted top tagging using the "Johns Hopkins" method from arXiv:0806.0848 (Kaplan, Rehermann, Schwartz and Tweedie) More...

class	JHTopTaggerStructure
	the structure returned by the JHTopTagger transformer. More...

class	MassDropTagger
	Class that helps perform 2-pronged boosted tagging using the "mass-drop" technique (with asymmetry cut) introduced by Jonathan Butterworth, Adam Davison, Mathieu Rubin and Gavin Salam in arXiv:0802.2470 in the context of a boosted Higgs search. More...

class	MassDropTaggerStructure
	the structure returned by the MassDropTagger transformer. More...

class	Pruner
	Transformer that prunes a jet. More...

class	PrunerStructure
	The structure associated with a PseudoJet thas has gone through a Pruner transformer. More...

class	Recluster
	Recluster a jet's constituents with a new jet definition. More...

class	RestFrameNSubjettinessTagger
	Class that helps perform 2-pronged boosted tagging using a reclustering in the jet's rest frame, supplemented with a cut on N-subjettiness (and a decay angle), as discussed by Ji-Hun Kim in arXiv:1011.1493. More...

class	RestFrameNSubjettinessTaggerStructure
	the structure returned by the RestFrameNSubjettinessTagger transformer. More...

class	Subtractor
	Class that helps perform jet background subtraction. More...

class	TopTaggerBase
	A base class that provides a common interface for top taggers that are able to return a W (in addition to the top itself). More...

class	TopTaggerBaseStructure
	class that specifies the structure common to all top taggers More...

class	Transformer
	Base (abstract) class for a jet transformer. More...

class	ATLASConePlugin
	Implementation of the ATLAS Cone (plugin for fastjet v2.4 upwards) More...

class	CMSIterativeConePlugin
	Implementation of the CMS Iterative Cone (plugin for fastjet v2.4 upwards) More...

class	CDFJetCluPlugin
	Implementation of the JetClu algorithm from CDF (plugin for fastjet-v2.1 upwards) More...

class	CDFMidPointPlugin
	Implementation of the MidPoint algorithm from CDF (plugin for fastjet-v2.1 upwards) More...

class	D0RunIIConePlugin
	Implementation of the D0 Run II Cone (plugin for fastjet v2.1 upwards) More...

class	D0RunIBaseConePlugin
	D0RunIBaseConePlugin is base class for a plugin for FastJet (v3.0 or later) that provides an interface to the D0 version of Run-I cone algorithm. More...

class	D0RunIConePlugin
	A plugin for FastJet (v3.0 or later) that provides an interface to the D0 version of Run-I cone algorithm. More...

class	D0RunIpre96ConePlugin
	A plugin for FastJet (v3.0 or later) that provides an interface to the pre 1996 D0 version of Run-I cone algorithm. More...

class	EECambridgePlugin
	Implementation of the e+e- Cambridge algorithm (plugin for fastjet v2.4 upwards) More...

class	JadePlugin
	Implementation of the e+e- Jade algorithm (plugin for fastjet v2.4 upwards) More...

class	NestedDefsPlugin
	Plugin to run multiple jet definitions successively (plugin for fastjet v2.4 upwards) More...

class	SISConeBaseExtras
	Class that provides extra information about a SISCone clustering. More...

class	SISConePlugin
	Implementation of the SISCone algorithm (plugin for fastjet v2.1 upwards) More...

class	SISConeExtras
	Class that provides extra information about a SISCone clustering. More...

class	SISConeSphericalPlugin
	Implementation of the spherical version of the SISCone algorithm (plugin for fastjet v2.1 upwards) More...

class	SISConeSphericalExtras
	Class that provides extra information about a SISCone clustering. More...

class	PxConePlugin
	Implementation of the PxCone algorithm (plugin for fastjet v2.1 upwards) More...

class	TrackJetPlugin
	Implementation of the TrackJet algorithm (plugin for fastjet v2.4 upwards) More...

class	GridJetPlugin
	plugin for fastjet (v3.0 upwards) that clusters particles such that all particles in a given cell of a rectangular rapidity-phi grid end up in a common "jet". More...

Typedefs
typedef ClusterSequenceActiveAreaExplicitGhosts	ClustSeqActAreaEG

typedef ClusterSequenceVoronoiArea::VoronoiAreaCalc	VAC

typedef ClusterSequenceAreaBase	ClusterSequenceWithArea

typedef GhostedAreaSpec	ActiveAreaSpec
	just provide a typedef for backwards compatibility with programs based on versions 2.0 and 2.1 of fastjet. More...

typedef JetAlgorithm	JetFinder
	make standard Les Houches nomenclature JetAlgorithm (algorithm is general recipe without the parameters) backward-compatible with old JetFinder

typedef integral_type< bool, true >	true_type
	the bool 'true' value promoted to a type

typedef integral_type< bool, false >	false_type
	the bool 'false' value promoted to a type

typedef char(&	__yes_type)[1]

typedef char(&	__no_type)[2]

typedef Tile2Base< 25 >	Tile25

typedef Tile2Base< 9 >	Tile2

typedef CGAL::Triangulation_vertex_base_with_info_2< InitialisedInt, K >	Vbb

typedef CGAL::Triangulation_hierarchy_vertex_base_2< Vbb >	Vb

typedef CGAL::Triangulation_face_base_2< K >	Fb

typedef CGAL::Triangulation_data_structure_2< Vb, Fb >	Tds

typedef CGAL::Delaunay_triangulation_2< K, Tds >	Dt

typedef CGAL::Triangulation_hierarchy_2< Dt >	Triangulation

typedef Triangulation::Vertex_handle	Vertex_handle

typedef Triangulation::Point	Point

typedef Triangulation::Vertex_circulator	Vertex_circulator
	CGAL Point structure.

typedef Triangulation::Face_circulator	Face_circulator

typedef Triangulation::Face_handle	Face_handle

Enumerations
enum	AreaType { invalid_area = -1 , active_area = 0 , active_area_explicit_ghosts = 1 , one_ghost_passive_area = 10 , passive_area = 11 , voronoi_area =20 }
	the different types of area that are supported

enum	Strategy { N2MHTLazy9AntiKtSeparateGhosts = -10 , N2MHTLazy9 = -7 , N2MHTLazy25 = -6 , N2MHTLazy9Alt = -5 , N2MinHeapTiled = -4 , N2Tiled = -3 , N2PoorTiled = -2 , N2Plain = -1 , N3Dumb = 0 , Best = 1 , NlnN = 2 , NlnN3pi = 3 , NlnN4pi = 4 , NlnNCam4pi = 14 , NlnNCam2pi2R = 13 , NlnNCam = 12 , BestFJ30 = 21 , plugin_strategy = 999 }
	the various options for the algorithmic strategy to adopt in clustering events with kt and cambridge style algorithms. More...

enum	JetAlgorithm { kt_algorithm =0 , cambridge_algorithm =1 , antikt_algorithm =2 , genkt_algorithm =3 , cambridge_for_passive_algorithm =11 , genkt_for_passive_algorithm =13 , ee_kt_algorithm =50 , ee_genkt_algorithm =53 , plugin_algorithm = 99 , undefined_jet_algorithm = 999 }
	the various families of jet-clustering algorithm More...

enum	RecombinationScheme { E_scheme =0 , pt_scheme =1 , pt2_scheme =2 , Et_scheme =3 , Et2_scheme =4 , BIpt_scheme =5 , BIpt2_scheme =6 , WTA_pt_scheme =7 , WTA_modp_scheme =8 , external_scheme = 99 }
	The various recombination schemes. More...

Functions
int	__default_random_generator (int *__iseed)

string	fastjet_version_string ()
	return a string containing information about the release

PseudoJet	join (const vector< PseudoJet > &pieces, const JetDefinition::Recombiner &recombiner)

PseudoJet	join (const PseudoJet &j1, const JetDefinition::Recombiner &recombiner)
	build a "CompositeJet" from a single PseudoJet with an extended structure of type T derived from CompositeJetStructure More...

PseudoJet	join (const PseudoJet &j1, const PseudoJet &j2, const JetDefinition::Recombiner &recombiner)
	build a "CompositeJet" from two PseudoJet with an extended structure of type T derived from CompositeJetStructure More...

PseudoJet	join (const PseudoJet &j1, const PseudoJet &j2, const PseudoJet &j3, const JetDefinition::Recombiner &recombiner)
	build a "CompositeJet" from 3 PseudoJet with an extended structure of type T derived from CompositeJetStructure More...

PseudoJet	join (const PseudoJet &j1, const PseudoJet &j2, const PseudoJet &j3, const PseudoJet &j4, const JetDefinition::Recombiner &recombiner)
	build a "CompositeJet" from 4 PseudoJet with an extended structure of type T derived from CompositeJetStructure More...

ostream &	operator<< (ostream &ostr, const TiledJet &jet)

PseudoJet	operator+ (const PseudoJet &jet1, const PseudoJet &jet2)

PseudoJet	operator- (const PseudoJet &jet1, const PseudoJet &jet2)

PseudoJet	operator* (double coeff, const PseudoJet &jet)

PseudoJet	operator* (const PseudoJet &jet, double coeff)

PseudoJet	operator/ (const PseudoJet &jet, double coeff)

bool	operator== (const PseudoJet &, const PseudoJet &)
	returns true if the 4 momentum components of the two PseudoJets are identical and all the internal indices (user, cluster_history) More...

bool	operator== (const PseudoJet &jet, const double val)
	Can only be used with val=0 and tests whether all four momentum components are equal to val (=0.0)

bool	have_same_momentum (const PseudoJet &jeta, const PseudoJet &jetb)
	returns true if the momenta of the two input jets are identical

PseudoJet	PtYPhiM (double pt, double y, double phi, double m)
	return a pseudojet with the given pt, y, phi and mass More...

void	sort_indices (vector< int > &indices, const vector< double > &values)

vector< PseudoJet >	sorted_by_pt (const vector< PseudoJet > &jets)
	return a vector of jets sorted into decreasing kt2

vector< PseudoJet >	sorted_by_rapidity (const vector< PseudoJet > &jets)
	return a vector of jets sorted into increasing rapidity

vector< PseudoJet >	sorted_by_E (const vector< PseudoJet > &jets)
	return a vector of jets sorted into decreasing energy

vector< PseudoJet >	sorted_by_pz (const vector< PseudoJet > &jets)
	return a vector of jets sorted into increasing pz

PseudoJet	join (const vector< PseudoJet > &pieces)

PseudoJet	join (const PseudoJet &j1)
	build a "CompositeJet" from a single PseudoJet with an extended structure of type T derived from CompositeJetStructure More...

PseudoJet	join (const PseudoJet &j1, const PseudoJet &j2)
	build a "CompositeJet" from two PseudoJet with an extended structure of type T derived from CompositeJetStructure More...

PseudoJet	join (const PseudoJet &j1, const PseudoJet &j2, const PseudoJet &j3)
	build a "CompositeJet" from 3 PseudoJet with an extended structure of type T derived from CompositeJetStructure More...

PseudoJet	join (const PseudoJet &j1, const PseudoJet &j2, const PseudoJet &j3, const PseudoJet &j4)
	build a "CompositeJet" from 4 PseudoJet with an extended structure of type T derived from CompositeJetStructure More...

Selector	SelectorIdentity ()

Selector	operator! (const Selector &s)
	logical not applied on a selector More...

Selector	operator&& (const Selector &s1, const Selector &s2)
	logical and between two selectors More...

Selector	operator\|\| (const Selector &s1, const Selector &s2)
	logical or between two selectors More...

Selector	operator* (const Selector &s1, const Selector &s2)
	successive application of 2 selectors More...

Selector	SelectorPtMin (double ptmin)
	select objects with pt >= ptmin

Selector	SelectorPtMax (double ptmax)
	select objects with pt <= ptmax

Selector	SelectorPtRange (double ptmin, double ptmax)
	select objects with ptmin <= pt <= ptmax

Selector	SelectorEtMin (double Etmin)
	select objects with Et >= Etmin

Selector	SelectorEtMax (double Etmax)
	select objects with Et <= Etmax

Selector	SelectorEtRange (double Etmin, double Etmax)
	select objects with Etmin <= Et <= Etmax

Selector	SelectorEMin (double Emin)
	select objects with E >= Emin

Selector	SelectorEMax (double Emax)
	select objects with E <= Emax

Selector	SelectorERange (double Emin, double Emax)
	select objects with Emin <= E <= Emax

Selector	SelectorMassMin (double Mmin)
	select objects with Mass >= Mmin

Selector	SelectorMassMax (double Mmax)
	select objects with Mass <= Mmax

Selector	SelectorMassRange (double Mmin, double Mmax)
	select objects with Mmin <= Mass <= Mmax

Selector	SelectorRapMin (double rapmin)
	select objects with rap >= rapmin

Selector	SelectorRapMax (double rapmax)
	select objects with rap <= rapmax

Selector	SelectorRapRange (double rapmin, double rapmax)
	select objects with rapmin <= rap <= rapmax

Selector	SelectorAbsRapMin (double absrapmin)
	select objects with \|rap\| >= absrapmin

Selector	SelectorAbsRapMax (double absrapmax)
	select objects with \|rap\| <= absrapmax

Selector	SelectorAbsRapRange (double absrapmin, double absrapmax)
	select objects with absrapmin <= \|rap\| <= absrapmax

Selector	SelectorEtaMin (double etamin)
	select objects with eta >= etamin

Selector	SelectorEtaMax (double etamax)
	select objects with eta <= etamax

Selector	SelectorEtaRange (double etamin, double etamax)
	select objects with etamin <= eta <= etamax

Selector	SelectorAbsEtaMin (double absetamin)
	select objects with \|eta\| >= absetamin

Selector	SelectorAbsEtaMax (double absetamax)
	select objects with \|eta\| <= absetamax

Selector	SelectorAbsEtaRange (double absetamin, double absetamax)
	select objects with absetamin <= \|eta\| <= absetamax

Selector	SelectorPhiRange (double phimin, double phimax)
	select objects with phimin <= phi <= phimax

Selector	SelectorRapPhiRange (double rapmin, double rapmax, double phimin, double phimax)
	select objects with rapmin <= rap <= rapmax && phimin <= phi <= phimax More...

Selector	SelectorNHardest (unsigned int n)
	select the n hardest objects

Selector	SelectorCircle (const double radius)
	select objets within a distance 'radius' from the location of the reference jet, set by Selector::set_reference(...)

Selector	SelectorDoughnut (const double radius_in, const double radius_out)
	select objets with distance from the reference jet is between 'radius_in' and 'radius_out'; the reference jet is set by Selector::set_reference(...)

Selector	SelectorStrip (const double half_width)
	select objets within a rapidity distance 'half_width' from the location of the reference jet, set by Selector::set_reference(...)

Selector	SelectorRectangle (const double half_rap_width, const double half_phi_width)
	select objets within rapidity distance 'half_rap_width' from the reference jet and azimuthal-angle distance within 'half_phi_width'; the reference jet is set by Selector::set_reference(...)

Selector	SelectorPtFractionMin (double fraction)
	select objects that carry at least a fraction "fraction" of the reference jet. More...

Selector	SelectorIsZero ()
	select PseudoJet with 0 momentum

Selector	SelectorIsPureGhost ()
	select objects that are (or are only made of) ghosts. More...

int	scomp (const void p1, const void p2)

template<typename T >
PseudoJet	join (const std::vector< PseudoJet > &pieces)
	build a "CompositeJet" from the vector of its pieces with an extended structure of type T derived from CompositeJetStructure More...

template<typename T >
PseudoJet	join (const std::vector< PseudoJet > &pieces, const JetDefinition::Recombiner &recombiner)
	build a "CompositeJet" from the vector of its pieces with an extended structure of type T derived from CompositeJetStructure More...

bool	operator!= (const PseudoJet &a, const PseudoJet &b)
	inequality test which is exact opposite of operator==

bool	operator== (const double val, const PseudoJet &jet)

bool	operator!= (const PseudoJet &a, const double val)
	Can only be used with val=0 and tests whether at least one of the four momentum components is different from val (=0.0)

bool	operator!= (const double val, const PseudoJet &a)

double	dot_product (const PseudoJet &a, const PseudoJet &b)
	returns the 4-vector dot product of a and b

double	cos_theta (const PseudoJet &a, const PseudoJet &b)
	returns the cosine of the angle between a and b

double	theta (const PseudoJet &a, const PseudoJet &b)
	returns the angle between a and b

std::vector< PseudoJet >	sorted_by_pt (const std::vector< PseudoJet > &jets)
	return a vector of jets sorted into decreasing transverse momentum

std::vector< PseudoJet >	sorted_by_rapidity (const std::vector< PseudoJet > &jets)
	return a vector of jets sorted into increasing rapidity

std::vector< PseudoJet >	sorted_by_E (const std::vector< PseudoJet > &jets)
	return a vector of jets sorted into decreasing energy

std::vector< PseudoJet >	sorted_by_pz (const std::vector< PseudoJet > &jets)
	return a vector of jets sorted into increasing pz

void	sort_indices (std::vector< int > &indices, const std::vector< double > &values)
	sort the indices so that values[indices[0->n-1]] is sorted into increasing order

template<class T >
std::vector< T >	objects_sorted_by_values (const std::vector< T > &objects, const std::vector< double > &values)
	given a vector of values with a one-to-one correspondence with the vector of objects, sort objects into an order such that the associated values would be in increasing order (but don't actually touch the values vector in the process).

template<class T , class U >
bool	operator== (SharedPtr< T > const &t, SharedPtr< U > const &u)
	comparison: equality

template<class T , class U >
bool	operator!= (SharedPtr< T > const &t, SharedPtr< U > const &u)
	comparison: difference

template<class T , class U >
bool	operator< (SharedPtr< T > const &t, SharedPtr< U > const &u)
	comparison: orgering

template<class T >
void	swap (SharedPtr< T > &a, SharedPtr< T > &b)
	swapping

template<class T >
T *	get_pointer (SharedPtr< T > const &t)
	getting the pointer

bool	floor_ln2_less (unsigned x, unsigned y)
	returns true if floor(ln_base2(x)) < floor(ln_base2(y)), using Chan's neat trick...

template<class B , class D >
B *	cast_if_derived (D *d)
	a little helper that returns a pointer to d of type B* if D is derived from B and NULL otherwise

double	norm (const VPoint p)
	norm of a vector

double	vector_product (const VPoint &p1, const VPoint &p2)
	2D vector product

double	scalar_product (const VPoint &p1, const VPoint &p2)
	scalar product

template<class T >
T	deltaPhi (T phi1, T phi2)

template<class T >
T	deltaR2 (T eta1, T phi1, T eta2, T phi2)

Variables
BasicRandom< int >	_G_random_int

BasicRandom< double >	_G_random_double

const unsigned int	twopow31 = 2147483648U

const JetAlgorithm	aachen_algorithm = cambridge_algorithm
	provide other possible names for the Cambridge/Aachen algorithm

const JetAlgorithm	cambridge_aachen_algorithm = cambridge_algorithm

const double	MaxRap = 1e5
	Used to protect against parton-level events where pt can be zero for some partons, giving rapidity=infinity. More...

const double	pseudojet_invalid_phi = -100.0
	default value for phi, meaning it (and rapidity) have yet to be calculated)

const double	pseudojet_invalid_rap = -1e200

const double	tile_edge_security_margin =1.0e-7
	Rounding errors in the Lazy strategies may cause the following problem: when browsing tiles in the vicinity of the particles being clustered in order to decide which of these tiles may contain particles that need to be updated (because theit NN is one of the particles that are currently clustered), we discard tiles that are deemed "too far from the cell" by the "max_NN_dist" criterion. More...

const int	n_tile_neighbours = 9

const double	pi = 3.141592653589793238462643383279502884197

const double	twopi = 6.283185307179586476925286766559005768394

const double	pisq = 9.869604401089358618834490999876151135314

const double	zeta2 = 1.644934066848226436472415166646025189219

const double	zeta3 = 1.202056903159594285399738161511449990765

const double	eulergamma = 0.577215664901532860606512090082402431042

const double	ln2 = 0.693147180559945309417232121458176568076

const int	INFINITE_VERTEX =-1

const int	NEW_VERTEX =-2

const double	HUGE_DOUBLE =1e300

Detailed Description

the FastJet namespace

The code in this file is supposed to help writing code that will automatically provide thread-safe features when available and come revert back to "old/standard" C++ if thread-safety is not switched on.

all the fastjet-related material is put under that namespace

\TODO fix doxygen comments (declare things as internal; make sure doxygen doc is not duplicate — if necessary, keep only doxygen comments in the thread-safe versions)

Typedef Documentation

◆ ActiveAreaSpec

typedef GhostedAreaSpec fastjet::ActiveAreaSpec

just provide a typedef for backwards compatibility with programs based on versions 2.0 and 2.1 of fastjet.

Since there is no easy way of telling people this is deprecated at compile or run time, we should be careful before removing this in the future.

Definition at line 381 of file GhostedAreaSpec.hh.

Enumeration Type Documentation

◆ Strategy

enum fastjet::Strategy

the various options for the algorithmic strategy to adopt in clustering events with kt and cambridge style algorithms.

Enumerator
N2MHTLazy9AntiKtSeparateGhosts	Like N2MHTLazy9 in a number of respects, but does not calculate ghost-ghost distances and so does not carry out ghost-ghost recombination. If you want active ghosted areas, then this is only suitable for use with the anti-kt algorithm (or genkt with negative p), and does not produce any pure ghost jets. If used with active areas with Kt or Cam algorithms it will actually produce a passive area. Particles are deemed to be ghosts if their pt is below a threshold (currently 1e-50, hard coded as ghost_limit in LazyTiling9SeparateGhosts). Currently for events with a couple of thousand normal particles and O(10k) ghosts, this can be quicker than N2MHTLazy9, which would otherwise be the best strategy. New in FJ3.1
N2MHTLazy9	only looks into a neighbouring tile for a particle's nearest neighbour (NN) if that particle's in-tile NN is further than the distance to the edge of the neighbouring tile. Uses tiles of size R and a 3x3 tile grid around the particle. New in FJ3.1
N2MHTLazy25	Similar to N2MHTLazy9, but uses tiles of size R/2 and a 5x5 tile grid around the particle. New in FJ3.1
N2MHTLazy9Alt	Like to N2MHTLazy9 but uses slightly different optimizations, e.g. for calculations of distance to nearest tile; as of 2014-07-18 it is slightly slower and not recommended for production use. To considered deprecated. New in FJ3.1
N2MinHeapTiled	faster that N2Tiled above about 500 particles; differs from it by retainig the di(closest j) distances in a MinHeap (sort of priority queue) rather than a simple vector.
N2Tiled	fastest from about 50..500
N2PoorTiled	legacy
N2Plain	fastest below 50
N3Dumb	worse even than the usual N^3 algorithms
Best	automatic selection of the best (based on N), including the LazyTiled strategies that are new to FJ3.1
NlnN	best of the NlnN variants – best overall for N>10^4. (Does not work for R>=2pi)
NlnN3pi	legacy N ln N using 3pi coverage of cylinder. (Does not work for R>=2pi)
NlnN4pi	legacy N ln N using 4pi coverage of cylinder
NlnNCam4pi	Chan's closest pair method (in a variant with 4pi coverage), for use exclusively with the Cambridge algorithm. (Does not work for R>=2pi)
NlnNCam2pi2R	Chan's closest pair method (in a variant with 2pi+2R coverage), for use exclusively with the Cambridge algorithm. (Does not work for R>=2pi)
NlnNCam	Chan's closest pair method (in a variant with 2pi+minimal extra variant), for use exclusively with the Cambridge algorithm. (Does not work for R>=2pi)
BestFJ30	the automatic strategy choice that was being made in FJ 3.0 (restricted to strategies that were present in FJ 3.0)
plugin_strategy	the plugin has been used...

Definition at line 51 of file JetDefinition.hh.

◆ JetAlgorithm

enum fastjet::JetAlgorithm

the various families of jet-clustering algorithm

Enumerator
kt_algorithm	the longitudinally invariant kt algorithm
cambridge_algorithm	the longitudinally invariant variant of the cambridge algorithm (aka Aachen algoithm).
antikt_algorithm	like the k_t but with distance measures dij = min(1/kti^2,1/ktj^2) Delta R_{ij}^2 / R^2 diB = 1/kti^2
genkt_algorithm	like the k_t but with distance measures dij = min(kti^{2p},ktj^{2p}) Delta R_{ij}^2 / R^2 diB = 1/kti^{2p} where p = extra_param()
cambridge_for_passive_algorithm	a version of cambridge with a special distance measure for particles whose pt is < extra_param(); this is not usually intended for end users, but is instead automatically selected when requesting a passive Cambridge area.
genkt_for_passive_algorithm	a version of genkt with a special distance measure for particles whose pt is < extra_param() [relevant for passive areas when p<=0] *** NB: THERE IS CURRENTLY NO IMPLEMENTATION FOR THIS ALG *****
ee_kt_algorithm	the e+e- kt algorithm
ee_genkt_algorithm	the e+e- genkt algorithm (R > 2 and p=1 gives ee_kt)
plugin_algorithm	any plugin algorithm supplied by the user
undefined_jet_algorithm	the value for the jet algorithm in a JetDefinition for which no algorithm has yet been defined

Definition at line 137 of file JetDefinition.hh.

◆ RecombinationScheme

enum fastjet::RecombinationScheme

The various recombination schemes.

Note that the schemes that recombine with non-linear weighting of the directions (e.g. pt2, winner-takes-all) are collinear safe only for algorithms with a suitable ordering of the recombinations: orderings in which, for particles of comparable energies, small-angle clusterings take place before large-angle clusterings. This property is satisfied by all gen-kt algorithms.

Enumerator
E_scheme	summing the 4-momenta
pt_scheme	pt weighted recombination of y,phi (and summing of pt's) with preprocessing to make things massless by rescaling E=\|\vec p\|
pt2_scheme	pt^2 weighted recombination of y,phi (and summing of pt's) with preprocessing to make things massless by rescaling E=\|\vec p\|
Et_scheme	pt weighted recombination of y,phi (and summing of pt's) with preprocessing to make things massless by rescaling \|\vec p\|->=E
Et2_scheme	pt^2 weighted recombination of y,phi (and summing of pt's) with preprocessing to make things massless by rescaling \|\vec p\|->=E
BIpt_scheme	pt weighted recombination of y,phi (and summing of pt's), with no preprocessing
BIpt2_scheme	pt^2 weighted recombination of y,phi (and summing of pt's) no preprocessing
WTA_pt_scheme	pt-based Winner-Takes-All (WTA) recombination: the result of the recombination has the rapidity, azimuth and mass of the PseudoJet with the larger pt, and a pt equal to the sum of the two pt's
WTA_modp_scheme	mod-p-based Winner-Takes-All (WTA) recombination: the result of the recombination gets the 3-vector direction and mass of the PseudoJet with the larger \|3-momentum\| (modp), and a \|3-momentum\| equal to the scalar sum of the two \|3-momenta\|.
external_scheme	for the user's external scheme

Definition at line 193 of file JetDefinition.hh.

Function Documentation

◆ join() [1/10]

PseudoJet fastjet::join	(	const PseudoJet &	j1,
		const JetDefinition::Recombiner &	recombiner
	)

build a "CompositeJet" from a single PseudoJet with an extended structure of type T derived from CompositeJetStructure

build a MergedJet from a single PseudoJet

Definition at line 476 of file JetDefinition.cc.

◆ join() [2/10]

PseudoJet fastjet::join	(	const PseudoJet &	j1,
		const PseudoJet &	j2,
		const JetDefinition::Recombiner &	recombiner
	)

build a "CompositeJet" from two PseudoJet with an extended structure of type T derived from CompositeJetStructure

build a MergedJet from 2 PseudoJet

Definition at line 482 of file JetDefinition.cc.

◆ join() [3/10]

PseudoJet fastjet::join	(	const PseudoJet &	j1,
		const PseudoJet &	j2,
		const PseudoJet &	j3,
		const JetDefinition::Recombiner &	recombiner
	)

build a "CompositeJet" from 3 PseudoJet with an extended structure of type T derived from CompositeJetStructure

build a MergedJet from 3 PseudoJet

Definition at line 491 of file JetDefinition.cc.

◆ join() [4/10]

PseudoJet fastjet::join	(	const PseudoJet &	j1,
		const PseudoJet &	j2,
		const PseudoJet &	j3,
		const PseudoJet &	j4,
		const JetDefinition::Recombiner &	recombiner
	)

build a "CompositeJet" from 4 PseudoJet with an extended structure of type T derived from CompositeJetStructure

build a MergedJet from 4 PseudoJet

Definition at line 501 of file JetDefinition.cc.

◆ operator==()

bool fastjet::operator==	(	const PseudoJet &	,
		const PseudoJet &
	)

returns true if the 4 momentum components of the two PseudoJets are identical and all the internal indices (user, cluster_history)

structure and user-info shared pointers are too

Definition at line 356 of file PseudoJet.cc.

◆ PtYPhiM()

PseudoJet fastjet::PtYPhiM	(	double	pt,
		double	y,
		double	phi,
		double	m
	)

return a pseudojet with the given pt, y, phi and mass

return a pseudojet with the given pt, y, phi and mass (phi should satisfy -2pi<phi<4pi)

Definition at line 469 of file PseudoJet.cc.

◆ join() [5/10]

PseudoJet fastjet::join ( const PseudoJet & j1 )

build a "CompositeJet" from a single PseudoJet with an extended structure of type T derived from CompositeJetStructure

build a MergedJet from a single PseudoJet

Definition at line 939 of file PseudoJet.cc.

◆ join() [6/10]

PseudoJet fastjet::join	(	const PseudoJet &	j1,
		const PseudoJet &	j2
	)

build a "CompositeJet" from two PseudoJet with an extended structure of type T derived from CompositeJetStructure

build a MergedJet from 2 PseudoJet

Definition at line 944 of file PseudoJet.cc.

◆ join() [7/10]

PseudoJet fastjet::join	(	const PseudoJet &	j1,
		const PseudoJet &	j2,
		const PseudoJet &	j3
	)

build a "CompositeJet" from 3 PseudoJet with an extended structure of type T derived from CompositeJetStructure

build a MergedJet from 3 PseudoJet

Definition at line 953 of file PseudoJet.cc.

◆ join() [8/10]

PseudoJet fastjet::join	(	const PseudoJet &	j1,
		const PseudoJet &	j2,
		const PseudoJet &	j3,
		const PseudoJet &	j4
	)

build a "CompositeJet" from 4 PseudoJet with an extended structure of type T derived from CompositeJetStructure

build a MergedJet from 4 PseudoJet

Definition at line 963 of file PseudoJet.cc.

◆ join() [9/10]

template<typename T >

PseudoJet fastjet::join ( const std::vector< PseudoJet > & pieces )

build a "CompositeJet" from the vector of its pieces with an extended structure of type T derived from CompositeJetStructure

build a "CompositeJet" from the vector of its pieces

In this case, E-scheme recombination is assumed to compute the total momentum

Definition at line 155 of file CompositeJetStructure.hh.

◆ join() [10/10]

template<typename T >

PseudoJet fastjet::join	(	const std::vector< PseudoJet > &	pieces,
		const JetDefinition::Recombiner &	recombiner
	)

build a "CompositeJet" from the vector of its pieces with an extended structure of type T derived from CompositeJetStructure

build a "CompositeJet" from the vector of its pieces

In this case, E-scheme recombination is assumed to compute the total momentum

Definition at line 218 of file CompositeJetStructure.hh.

Variable Documentation

◆ MaxRap

const double fastjet::MaxRap = 1e5

Used to protect against parton-level events where pt can be zero for some partons, giving rapidity=infinity.

KtJet fails in those cases.

Definition at line 53 of file PseudoJet.hh.

◆ tile_edge_security_margin

const double fastjet::tile_edge_security_margin =1.0e-7

Rounding errors in the Lazy strategies may cause the following problem: when browsing tiles in the vicinity of the particles being clustered in order to decide which of these tiles may contain particles that need to be updated (because theit NN is one of the particles that are currently clustered), we discard tiles that are deemed "too far from the cell" by the "max_NN_dist" criterion.

Because of rounding error, this condition can sometimes miss cases where an update is needed.

An example of this happens if a particle '1' is, say, at the lower edge of the rapidity of a given tile, with a particle '2' in the tile directly on its left at the same rapidity. Assume also that max_NN_dist in 2's tile corresponds to the distance between 2 and teh tile of 1. If 2 is 1's NN then in case 2 gets clustered, 1's NN needs to be updated. However, rounding errors in the calculation of the distance between 1 and 2 may result is something slightly larger than the max_NN_dist in 2's tile.

This situation corresponds to the bug reported by Jochen Olt on February 12 2015 [see issue-tracker/2015-02-infinite-loop], causing an infinite loop.

To prevent this, the simplest solution is, when looking at tiles to browse for updateds, to add a margin of security close to the edges of the cell, i.e. instead of updating only tiles for which distance<=max_NN_dist, we will update tiles for which distance<=max_NN_dist+tile_edge_security_margin.

Note that this does not need to be done when computing nearest neighbours [rounding errors are tolerated there] but it is critical when tracking points that have to be updated.

Definition at line 71 of file LazyTiling9Alt.hh.

Namespaces

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