Main Page | Namespace List | Class Hierarchy | Class List | Directories | File List | Namespace Members | Class Members | File Members
fastjet::PseudoJet

fastjet::PseudoJet Class Reference

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

#include <PseudoJet.hh>

List of all members.

Public Types

enum  {
  X = 0, Y = 1, Z = 2, T = 3,
  NUM_COORDINATES = 4, SIZE = NUM_COORDINATES
}

Public Member Functions

 PseudoJet ()
 PseudoJet (const double px, const double py, const double pz, const double E)
 construct a pseudojet from explicit components
template<class L>
 PseudoJet (const L &some_four_vector)
 constructor from any object that has px,py,pz,E = some_four_vector[0--3],
double E () const
double e () const
double px () const
double py () const
double pz () const
const double phi () const
 returns phi (in the range 0..2pi)
const double phi_std () const
 returns phi in the range -pi..pi
const double phi_02pi () const
 returns phi in the range 0..2pi
double rap () const
 returns the rapidity or some large value when the rapidity is infinite
double rapidity () const
 the same as rap()
double kt2 () const
 returns the squared transverse momentum
double perp2 () const
 returns the squared transverse momentum
double perp () const
 returns the scalar transverse momentum
double m2 () const
 returns the squared invariant mass // like CLHEP
double mperp2 () const
 returns the squared transverse mass = kt^2+m^2
double mperp () const
 returns the transverse mass = sqrt(kt^2+m^2)
double m () const
 returns the invariant mass (If m2() is negative then -sqrt(-m2()) is returned, as in CLHEP)
double operator() (int i) const
 returns component i, where X==0, Y==1, Z==2, E==3
double operator[] (int i) const
 returns component i, where X==0, Y==1, Z==2, E==3
PseudoJet & boost (const PseudoJet &prest)
 transform this jet (given in the rest frame of prest) into a jet in the lab frame;
PseudoJet & unboost (const PseudoJet &prest)
 transform this jet (given in the rest frame of prest) into a jet in the lab frame;
const int & cluster_hist_index () const
 return the cluster_hist_index, intended to be used by clustering routines.
void set_cluster_hist_index (const int index)
 set the cluster_hist_index, intended to be used by clustering routines.
const int cluster_sequence_history_index () const
 alternative name for cluster_hist_index() [perhaps more meaningful]
void set_cluster_sequence_history_index (const int index)
 alternative name for set_cluster_hist_index(.
const int & user_index () const
 return the user_index, intended to allow the user to "add" information
void set_user_index (const int index)
 set the user_index, intended to allow the user to "add" information
std::valarray< double > four_mom () const
 return a valarray containing the four-momentum (components 0-2 are 3-mom, component 3 is energy).
double kt_distance (const PseudoJet &other) const
 returns kt distance (R=1) between this jet and another
double plain_distance (const PseudoJet &other) const
 returns squared cylinder (rap-phi) distance between this jet and another
double squared_distance (const PseudoJet &other) const
 returns squared cylinder (rap-phi) distance between this jet and another
double beam_distance () const
 returns distance between this jet and the beam
void operator *= (double)
 multiply the jet's momentum by the coefficient
void operator/= (double)
 divide the jet's momentum by the coefficient
void operator+= (const PseudoJet &)
 add the other jet's momentum to this jet
void operator-= (const PseudoJet &)
 subtract the other jet's momentum from this jet
template<>
 PseudoJet (const Cmomentum &four_vector)
 shortcut for converting siscone Cmomentum into PseudoJet

Private Member Functions

void _finish_init ()
 do standard end of initialisation

Private Attributes

double _px
double _py
double _pz
double _E
double _phi
double _rap
double _kt2
int _cluster_hist_index
int _user_index

Detailed Description

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

Definition at line 54 of file PseudoJet.hh.

Member Enumeration Documentation

anonymous enum
 

Enumeration values:
X 
Y 
Z 
T 
NUM_COORDINATES 
SIZE 

Definition at line 111 of file PseudoJet.hh.

00111 { X=0, Y=1, Z=2, T=3, NUM_COORDINATES=4, SIZE=NUM_COORDINATES };

Constructor & Destructor Documentation

fastjet::PseudoJet::PseudoJet (   )  [inline]
 

Definition at line 56 of file PseudoJet.hh.

Referenced by PseudoJet().

00056 {};

fastjet::PseudoJet::PseudoJet (  const double  px,
const double  py,
const double  pz,
const double  E
) 
 

construct a pseudojet from explicit components

Definition at line 46 of file PseudoJet.cc.

References _E, _finish_init(), _px, _py, _pz, set_cluster_hist_index(), and set_user_index().

00046                                                                                       {
00047   
00048   _E  = E ;
00049   _px = px;
00050   _py = py;
00051   _pz = pz;
00052 
00053   this->_finish_init();
00054 
00055   // some default values for these two indices
00056   set_cluster_hist_index(-1);
00057   set_user_index(-1);
00058 
00059 }

template<class L>
fastjet::PseudoJet::PseudoJet (  const L &  some_four_vector  )  [inline]
 

constructor from any object that has px,py,pz,E = some_four_vector[0--3],

Definition at line 236 of file PseudoJet.hh.

References _E, _finish_init(), _px, _py, _pz, set_cluster_hist_index(), and set_user_index().

00236                                                                           {
00237 
00238   _px = some_four_vector[0];
00239   _py = some_four_vector[1];
00240   _pz = some_four_vector[2];
00241   _E  = some_four_vector[3];
00242   this->_finish_init();
00243   // some default values for these two indices
00244   set_cluster_hist_index(-1);
00245   set_user_index(-1);
00246 }

template<>
fastjet::PseudoJet::PseudoJet (  const Cmomentum &  four_vector  ) 
 

shortcut for converting siscone Cmomentum into PseudoJet

Definition at line 51 of file SISConePlugin.cc.

References PseudoJet().

00051                                                              {
00052   (*this) = PseudoJet(four_vector.px,four_vector.py,four_vector.pz,
00053                       four_vector.E);
00054 }

Member Function Documentation

void fastjet::PseudoJet::_finish_init (   )  [private]
 

do standard end of initialisation

Definition at line 64 of file PseudoJet.cc.

References _E, _kt2, _phi, _pz, _rap, m2(), fastjet::MaxRap, px(), py(), and fastjet::twopi.

Referenced by boost(), operator+=(), operator-=(), PseudoJet(), and unboost().

00064                               {
00065   _kt2 = this->px()*this->px() + this->py()*this->py();
00066   if (_kt2 == 0.0) {
00067     _phi = 0.0; } 
00068   else {
00069     _phi = atan2(this->py(),this->px());
00070   }
00071   if (_phi < 0.0) {_phi += twopi;}
00072   if (_phi >= twopi) {_phi -= twopi;} // can happen if phi=-|eps<1e-15|?
00073   if (this->E() == abs(this->pz()) && _kt2 == 0) {
00074     // Point has infinite rapidity -- convert that into a very large
00075     // number, but in such a way that different 0-pt momenta will have
00076     // different rapidities (so as to lift the degeneracy between
00077     // them) [this can be relevant at parton-level]
00078     double MaxRapHere = MaxRap + abs(this->pz());
00079     if (this->pz() >= 0.0) {_rap = MaxRapHere;} else {_rap = -MaxRapHere;}
00080   } else {
00081     // get the rapidity in a way that's modestly insensitive to roundoff
00082     // error when things pz,E are large (actually the best we can do without
00083     // explicit knowledge of mass)
00084     double effective_m2 = max(0.0,m2()); // force non tachyonic mass
00085     double E_plus_pz    = _E + abs(_pz); // the safer of p+, p-
00086     // p+/p- = (p+ p-) / (p-)^2 = (kt^2+m^2)/(p-)^2
00087     _rap = 0.5*log((_kt2 + effective_m2)/(E_plus_pz*E_plus_pz));
00088     if (_pz > 0) {_rap = - _rap;}
00089   }
00090 
00092   //if (this->E() != abs(this->pz())) {
00093   //  _rap = 0.5*log((this->E() + this->pz())/(this->E() - this->pz()));
00094   //    } else {
00095   //  // Overlapping points can give problems. Let's lift the degeneracy
00096   //  // in case of multiple 0-pT points (can be found at parton-level)
00097   //  double MaxRapHere = MaxRap + abs(this->pz());
00098   //  if (this->pz() >= 0.0) {_rap = MaxRapHere;} else {_rap = -MaxRapHere;}
00099   //}
00100 }

double fastjet::PseudoJet::beam_distance (   )  const [inline]
 

returns distance between this jet and the beam

Definition at line 161 of file PseudoJet.hh.

00161 {return _kt2;};

PseudoJet & fastjet::PseudoJet::boost (  const PseudoJet &  prest  ) 
 

transform this jet (given in the rest frame of prest) into a jet in the lab frame;

Definition at line 222 of file PseudoJet.cc.

References _E, _finish_init(), _px, _py, _pz, E(), m(), px(), py(), and pz().

00222                                                     {
00223   
00224   if (prest.px() == 0.0 && prest.py() == 0.0 && prest.pz() == 0.0) 
00225     return *this;
00226 
00227   double m = prest.m();
00228   assert(m != 0);
00229 
00230   double pf4  = (  px()*prest.px() + py()*prest.py()
00231                  + pz()*prest.pz() + E()*prest.E() )/m;
00232   double fn   = (pf4 + E()) / (prest.E() + m);
00233   _px +=  fn*prest.px();
00234   _py +=  fn*prest.py();
00235   _pz +=  fn*prest.pz();
00236   _E = pf4;
00237 
00238   _finish_init(); // we need to recalculate phi,rap,kt2
00239   return *this;
00240 }

const int& fastjet::PseudoJet::cluster_hist_index (   )  const [inline]
 

return the cluster_hist_index, intended to be used by clustering routines.

Definition at line 123 of file PseudoJet.hh.

Referenced by fastjet::ClusterSequence::add_constituents(), fastjet::ClusterSequenceActiveArea::area(), fastjet::ClusterSequenceActiveAreaExplicitGhosts::area_4vector(), fastjet::ClusterSequenceActiveArea::area_4vector(), fastjet::ClusterSequenceActiveArea::area_error(), and fastjet::ClusterSequenceActiveAreaExplicitGhosts::is_pure_ghost().

00123 {return _cluster_hist_index;};

const int fastjet::PseudoJet::cluster_sequence_history_index (   )  const [inline]
 

alternative name for cluster_hist_index() [perhaps more meaningful]

Definition at line 128 of file PseudoJet.hh.

00128                                                           {
00129     return cluster_hist_index();};

double fastjet::PseudoJet::e (   )  const [inline]
 

Definition at line 68 of file PseudoJet.hh.

Referenced by operator()().

00068 {return _E;}; // like CLHEP

double fastjet::PseudoJet::E (   )  const [inline]
 

Definition at line 67 of file PseudoJet.hh.

Referenced by fastjet::ClusterSequenceActiveArea::_transfer_areas(), boost(), fastjet::have_same_momentum(), fastjet::operator+(), fastjet::operator-(), fastjet::JetDefinition::DefaultRecombiner::preprocess(), print_jets(), fastjet::SISConePlugin::run_clustering(), fastjet::CDFJetCluPlugin::run_clustering(), and unboost().

00067 {return _E;};

valarray< double > fastjet::PseudoJet::four_mom (   )  const
 

return a valarray containing the four-momentum (components 0-2 are 3-mom, component 3 is energy).

Definition at line 105 of file PseudoJet.cc.

References _E, _px, _py, and _pz.

00105                                            {
00106   valarray<double> mom(4);
00107   mom[0] = _px;
00108   mom[1] = _py;
00109   mom[2] = _pz;
00110   mom[3] = _E ;
00111   return mom;
00112 }

double fastjet::PseudoJet::kt2 (   )  const [inline]
 

returns the squared transverse momentum

Definition at line 91 of file PseudoJet.hh.

Referenced by fastjet::ClusterSequence::jet_scale_for_algorithm().

00091 {return _kt2;};

double fastjet::PseudoJet::kt_distance (  const PseudoJet &  other  )  const
 

returns kt distance (R=1) between this jet and another

Definition at line 282 of file PseudoJet.cc.

References _kt2, _phi, _rap, fastjet::pi, and fastjet::twopi.

00282                                                            {
00283   //double distance = min(this->kt2(), other.kt2());
00284   double distance = min(_kt2, other._kt2);
00285   double dphi = abs(_phi - other._phi);
00286   if (dphi > pi) {dphi = twopi - dphi;}
00287   double drap = _rap - other._rap;
00288   distance = distance * (dphi*dphi + drap*drap);
00289   return distance;
00290 }

double fastjet::PseudoJet::m (   )  const [inline]
 

returns the invariant mass (If m2() is negative then -sqrt(-m2()) is returned, as in CLHEP)

Definition at line 258 of file PseudoJet.hh.

References m2().

Referenced by boost(), and unboost().

00258                                  {
00259   double mm = m2();
00260   return mm < 0.0 ? -std::sqrt(-mm) : std::sqrt(mm);
00261 }

double fastjet::PseudoJet::m2 (   )  const [inline]
 

returns the squared invariant mass // like CLHEP

Definition at line 97 of file PseudoJet.hh.

Referenced by _finish_init(), and m().

00097 {return (_E+_pz)*(_E-_pz)-_kt2;};

double fastjet::PseudoJet::mperp (   )  const [inline]
 

returns the transverse mass = sqrt(kt^2+m^2)

Definition at line 101 of file PseudoJet.hh.

00101 {return sqrt(std::abs(mperp2()));};

double fastjet::PseudoJet::mperp2 (   )  const [inline]
 

returns the squared transverse mass = kt^2+m^2

Definition at line 99 of file PseudoJet.hh.

00099 {return (_E+_pz)*(_E-_pz);};

void fastjet::PseudoJet::operator *= (  double   ) 
 

multiply the jet's momentum by the coefficient

Definition at line 179 of file PseudoJet.cc.

References _E, _kt2, _px, _py, and _pz.

00179                                        {
00180   _px *= coeff;
00181   _py *= coeff;
00182   _pz *= coeff;
00183   _E  *= coeff;
00184   _kt2*= coeff*coeff;
00185   // phi and rap are unchanged
00186 }

double fastjet::PseudoJet::operator() (  int  i  )  const
 

returns component i, where X==0, Y==1, Z==2, E==3

Definition at line 117 of file PseudoJet.cc.

References e(), px(), py(), pz(), T, X, Y, and Z.

00117                                           {
00118   switch(i) {
00119   case X:
00120     return px();
00121   case Y:
00122     return py();
00123   case Z:
00124     return pz();
00125   case T:
00126     return e();
00127   default:
00128     ostringstream err;
00129     err << "PseudoJet subscripting: bad index (" << i << ")";
00130     throw Error(err.str());
00131   }
00132   return 0.;
00133 }

void fastjet::PseudoJet::operator+= (  const PseudoJet &   ) 
 

add the other jet's momentum to this jet

Definition at line 197 of file PseudoJet.cc.

References _E, _finish_init(), _px, _py, and _pz.

00197                                                       {
00198   _px += other_jet._px;
00199   _py += other_jet._py;
00200   _pz += other_jet._pz;
00201   _E  += other_jet._E ;
00202   _finish_init(); // we need to recalculate phi,rap,kt2
00203 }

void fastjet::PseudoJet::operator-= (  const PseudoJet &   ) 
 

subtract the other jet's momentum from this jet

Definition at line 208 of file PseudoJet.cc.

References _E, _finish_init(), _px, _py, and _pz.

00208                                                       {
00209   _px -= other_jet._px;
00210   _py -= other_jet._py;
00211   _pz -= other_jet._pz;
00212   _E  -= other_jet._E ;
00213   _finish_init(); // we need to recalculate phi,rap,kt2
00214 }

void fastjet::PseudoJet::operator/= (  double   ) 
 

divide the jet's momentum by the coefficient

Definition at line 190 of file PseudoJet.cc.

00190                                        {
00191   (*this) *= 1.0/coeff;
00192 }

double fastjet::PseudoJet::operator[] (  int  i  )  const [inline]
 

returns component i, where X==0, Y==1, Z==2, E==3

Definition at line 108 of file PseudoJet.hh.

00108 { return (*this)(i); }; // this too

double fastjet::PseudoJet::perp (   )  const [inline]
 

returns the scalar transverse momentum

Definition at line 95 of file PseudoJet.hh.

Referenced by fastjet::ClusterSequenceActiveArea::_transfer_areas(), and fastjet::JetDefinition::DefaultRecombiner::recombine().

00095 {return sqrt(_kt2);};    // like CLHEP

double fastjet::PseudoJet::perp2 (   )  const [inline]
 

returns the squared transverse momentum

Definition at line 93 of file PseudoJet.hh.

Referenced by fastjet::ClusterSequenceActiveArea::_transfer_areas(), fastjet::ClusterSequence::inclusive_jets(), fastjet::JetDefinition::DefaultRecombiner::preprocess(), print_jets(), and fastjet::JetDefinition::DefaultRecombiner::recombine().

00093 {return _kt2;};  // like CLHEP

const double fastjet::PseudoJet::phi (   )  const [inline]
 

returns phi (in the range 0..2pi)

Definition at line 74 of file PseudoJet.hh.

Referenced by fastjet::JetDefinition::DefaultRecombiner::recombine().

00074 {return phi_02pi();};

const double fastjet::PseudoJet::phi_02pi (   )  const [inline]
 

returns phi in the range 0..2pi

Definition at line 81 of file PseudoJet.hh.

00081 {return _phi;};

const double fastjet::PseudoJet::phi_std (   )  const [inline]
 

returns phi in the range -pi..pi

Definition at line 77 of file PseudoJet.hh.

References fastjet::pi, and twopi.

00077                                        {
00078     return _phi > pi ? _phi-twopi : _phi;};

double fastjet::PseudoJet::plain_distance (  const PseudoJet &  other  )  const
 

returns squared cylinder (rap-phi) distance between this jet and another

Definition at line 295 of file PseudoJet.cc.

References _phi, _rap, fastjet::pi, and fastjet::twopi.

00295                                                               {
00296   double dphi = abs(_phi - other._phi);
00297   if (dphi > pi) {dphi = twopi - dphi;}
00298   double drap = _rap - other._rap;
00299   return (dphi*dphi + drap*drap);
00300 }

double fastjet::PseudoJet::px (   )  const [inline]
 

Definition at line 69 of file PseudoJet.hh.

Referenced by _finish_init(), fastjet::ClusterSequenceActiveArea::_transfer_areas(), boost(), fastjet::have_same_momentum(), operator()(), fastjet::operator+(), fastjet::operator-(), fastjet::JetDefinition::DefaultRecombiner::preprocess(), fastjet::SISConePlugin::run_clustering(), fastjet::CDFJetCluPlugin::run_clustering(), and unboost().

00069 {return _px;};

double fastjet::PseudoJet::py (   )  const [inline]
 

Definition at line 70 of file PseudoJet.hh.

Referenced by _finish_init(), fastjet::ClusterSequenceActiveArea::_transfer_areas(), boost(), fastjet::have_same_momentum(), operator()(), fastjet::operator+(), fastjet::operator-(), fastjet::JetDefinition::DefaultRecombiner::preprocess(), fastjet::SISConePlugin::run_clustering(), fastjet::CDFJetCluPlugin::run_clustering(), and unboost().

00070 {return _py;};

double fastjet::PseudoJet::pz (   )  const [inline]
 

Definition at line 71 of file PseudoJet.hh.

Referenced by fastjet::ClusterSequenceActiveArea::_transfer_areas(), boost(), fastjet::have_same_momentum(), operator()(), fastjet::operator+(), fastjet::operator-(), fastjet::JetDefinition::DefaultRecombiner::preprocess(), fastjet::SISConePlugin::run_clustering(), fastjet::CDFJetCluPlugin::run_clustering(), and unboost().

00071 {return _pz;};

double fastjet::PseudoJet::rap (   )  const [inline]
 

returns the rapidity or some large value when the rapidity is infinite

Definition at line 85 of file PseudoJet.hh.

Referenced by main(), and fastjet::JetDefinition::DefaultRecombiner::recombine().

00085 {return _rap;};

double fastjet::PseudoJet::rapidity (   )  const [inline]
 

the same as rap()

Definition at line 88 of file PseudoJet.hh.

00088 {return _rap;}; // like CLHEP

void fastjet::PseudoJet::set_cluster_hist_index (  const int  index  )  [inline]
 

set the cluster_hist_index, intended to be used by clustering routines.

Definition at line 125 of file PseudoJet.hh.

Referenced by PseudoJet().

00125 {_cluster_hist_index = index;};

void fastjet::PseudoJet::set_cluster_sequence_history_index (  const int  index  )  [inline]
 

alternative name for set_cluster_hist_index(.

..) [perhaps more meaningful]

Definition at line 132 of file PseudoJet.hh.

00132                                                                   {
00133     set_cluster_hist_index(index);};

void fastjet::PseudoJet::set_user_index (  const int  index  )  [inline]
 

set the user_index, intended to allow the user to "add" information

Definition at line 139 of file PseudoJet.hh.

Referenced by main(), fastjet::JetDefinition::DefaultRecombiner::preprocess(), PseudoJet(), fastjet::JetDefinition::DefaultRecombiner::recombine(), and fastjet::SISConePlugin::run_clustering().

00139 {_user_index = index;};

double fastjet::PseudoJet::squared_distance (  const PseudoJet &  other  )  const [inline]
 

returns squared cylinder (rap-phi) distance between this jet and another

Definition at line 152 of file PseudoJet.hh.

00152                                                                 {
00153     return plain_distance(other);};

PseudoJet & fastjet::PseudoJet::unboost (  const PseudoJet &  prest  ) 
 

transform this jet (given in the rest frame of prest) into a jet in the lab frame;

Definition at line 249 of file PseudoJet.cc.

References _E, _finish_init(), _px, _py, _pz, E(), m(), px(), py(), and pz().

00249                                                       {
00250   
00251   if (prest.px() == 0.0 && prest.py() == 0.0 && prest.pz() == 0.0) 
00252     return *this;
00253 
00254   double m = prest.m();
00255   assert(m != 0);
00256 
00257   double pf4  = ( -px()*prest.px() - py()*prest.py()
00258                  - pz()*prest.pz() + E()*prest.E() )/m;
00259   double fn   = (pf4 + E()) / (prest.E() + m);
00260   _px -=  fn*prest.px();
00261   _py -=  fn*prest.py();
00262   _pz -=  fn*prest.pz();
00263   _E = pf4;
00264 
00265   _finish_init(); // we need to recalculate phi,rap,kt2
00266   return *this;
00267 }

const int& fastjet::PseudoJet::user_index (   )  const [inline]
 

return the user_index, intended to allow the user to "add" information

Definition at line 137 of file PseudoJet.hh.

Referenced by fastjet::JetDefinition::DefaultRecombiner::preprocess().

00137 {return _user_index;};

Member Data Documentation

int fastjet::PseudoJet::_cluster_hist_index [private]
 

Definition at line 173 of file PseudoJet.hh.

double fastjet::PseudoJet::_E [private]
 

Definition at line 171 of file PseudoJet.hh.

Referenced by _finish_init(), boost(), four_mom(), operator *=(), operator+=(), operator-=(), PseudoJet(), and unboost().

double fastjet::PseudoJet::_kt2 [private]
 

Definition at line 172 of file PseudoJet.hh.

Referenced by _finish_init(), kt_distance(), and operator *=().

double fastjet::PseudoJet::_phi [private]
 

Definition at line 172 of file PseudoJet.hh.

Referenced by _finish_init(), kt_distance(), and plain_distance().

double fastjet::PseudoJet::_px [private]
 

Definition at line 171 of file PseudoJet.hh.

Referenced by boost(), four_mom(), operator *=(), operator+=(), operator-=(), PseudoJet(), and unboost().

double fastjet::PseudoJet::_py [private]
 

Definition at line 171 of file PseudoJet.hh.

Referenced by boost(), four_mom(), operator *=(), operator+=(), operator-=(), PseudoJet(), and unboost().

double fastjet::PseudoJet::_pz [private]
 

Definition at line 171 of file PseudoJet.hh.

Referenced by _finish_init(), boost(), four_mom(), operator *=(), operator+=(), operator-=(), PseudoJet(), and unboost().

double fastjet::PseudoJet::_rap [private]
 

Definition at line 172 of file PseudoJet.hh.

Referenced by _finish_init(), kt_distance(), and plain_distance().

int fastjet::PseudoJet::_user_index [private]
 

Definition at line 173 of file PseudoJet.hh.

The documentation for this class was generated from the following files:
Generated on Mon Apr 2 20:58:20 2007 for fastjet by  doxygen 1.4.2