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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 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
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 & 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 (eta-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

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 53 of file PseudoJet.hh.

Member Enumeration Documentation

anonymous enum
 

Enumeration values:
X 
Y 
Z 
T 
NUM_COORDINATES 
SIZE 

Definition at line 103 of file PseudoJet.hh.

00103 { X=0, Y=1, Z=2, T=3, NUM_COORDINATES=4, SIZE=NUM_COORDINATES };

Constructor & Destructor Documentation

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

Definition at line 55 of file PseudoJet.hh.

00055 {};

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, and _pz.

00046                                                                                       {
00047   
00048   _E  = E ;
00049   _px = px;
00050   _py = py;
00051   _pz = pz;
00052 
00053   this->_finish_init();
00054 };

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 207 of file PseudoJet.hh.

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

00207                                                                           {
00208 
00209   _px = some_four_vector[0];
00210   _py = some_four_vector[1];
00211   _pz = some_four_vector[2];
00212   _E  = some_four_vector[3];
00213   this->_finish_init();
00214 };

Member Function Documentation

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

do standard end of initialisation

Definition at line 59 of file PseudoJet.cc.

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

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

00059                               {
00060   _kt2 = this->px()*this->px() + this->py()*this->py();
00061   if (_kt2 == 0.0) {
00062     _phi = 0.0; } 
00063   else {
00064     _phi = atan2(this->py(),this->px());
00065   }
00066   if (_phi < 0.0) {_phi += twopi;}
00067   if (_phi >= twopi) {_phi -= twopi;} // can happen if phi=-|eps<1e-15|?
00068   if (this->E() == abs(this->pz()) && _kt2 == 0) {
00069     // Point has infinite rapidity -- convert that into a very large
00070     // number, but in such a way that different 0-pt momenta will have
00071     // different rapidities (so as to lift the degeneracy between
00072     // them) [this can be relevant at parton-level]
00073     double MaxRapHere = MaxRap + abs(this->pz());
00074     if (this->pz() >= 0.0) {_rap = MaxRapHere;} else {_rap = -MaxRapHere;}
00075   } else {
00076     // get the rapidity in a way that's modestly insensitive to roundoff
00077     // error when things pz,E are large (actually the best we can do without
00078     // explicit knowledge of mass)
00079     double effective_m2 = max(0.0,m2()); // force non tachyonic mass
00080     double E_plus_pz    = _E + abs(_pz); // the safer of p+, p-
00081     // p+/p- = (p+ p-) / (p-)^2 = (kt^2+m^2)/(p-)^2
00082     _rap = 0.5*log((_kt2 + effective_m2)/(E_plus_pz*E_plus_pz));
00083     if (_pz > 0) {_rap = - _rap;}
00084   }
00086   //if (this->E() != abs(this->pz())) {
00087   //  _rap = 0.5*log((this->E() + this->pz())/(this->E() - this->pz()));
00088   //    } else {
00089   //  // Overlapping points can give problems. Let's lift the degeneracy
00090   //  // in case of multiple 0-pT points (can be found at parton-level)
00091   //  double MaxRapHere = MaxRap + abs(this->pz());
00092   //  if (this->pz() >= 0.0) {_rap = MaxRapHere;} else {_rap = -MaxRapHere;}
00093   //}
00094 }

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

returns distance between this jet and the beam

Definition at line 133 of file PseudoJet.hh.

00133 {return _kt2;};

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

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

Definition at line 108 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().

00108 {return _cluster_hist_index;};

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

Definition at line 67 of file PseudoJet.hh.

Referenced by operator()().

00067 {return _E;}; // like CLHEP

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

Definition at line 66 of file PseudoJet.hh.

Referenced by fastjet::operator+(), fastjet::operator-(), and print_jets().

00066 {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 99 of file PseudoJet.cc.

References _E, _px, _py, and _pz.

00099                                            {
00100   valarray<double> mom(4);
00101   mom[0] = _px;
00102   mom[1] = _py;
00103   mom[2] = _pz;
00104   mom[3] = _E ;
00105   return mom;
00106 }

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

returns the squared transverse momentum

Definition at line 90 of file PseudoJet.hh.

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

00090 {return _kt2;};

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

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

Definition at line 213 of file PseudoJet.cc.

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

00213                                                            {
00214   //double distance = min(this->kt2(), other.kt2());
00215   double distance = min(_kt2, other._kt2);
00216   double dphi = abs(_phi - other._phi);
00217   if (dphi > pi) {dphi = twopi - dphi;}
00218   double drap = _rap - other._rap;
00219   distance = distance * (dphi*dphi + drap*drap);
00220   return distance;
00221 }

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

returns the squared invariant mass // like CLHEP

Definition at line 96 of file PseudoJet.hh.

Referenced by _finish_init().

00096 {return (_E+_pz)*(_E-_pz)-_kt2;};

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

multiply the jet's momentum by the coefficient

Definition at line 173 of file PseudoJet.cc.

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

00173                                        {
00174   _px *= coeff;
00175   _py *= coeff;
00176   _pz *= coeff;
00177   _E  *= coeff;
00178   _kt2*= coeff*coeff;
00179   // phi and rap are unchanged
00180 }

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

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

Definition at line 111 of file PseudoJet.cc.

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

00111                                           {
00112   switch(i) {
00113   case X:
00114     return px();
00115   case Y:
00116     return py();
00117   case Z:
00118     return pz();
00119   case T:
00120     return e();
00121   default:
00122     ostringstream err;
00123     err << "PseudoJet subscripting: bad index (" << i << ")";
00124     throw Error(err.str());
00125   }
00126   return 0.;
00127 }

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

add the other jet's momentum to this jet

Definition at line 191 of file PseudoJet.cc.

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

00191                                                       {
00192   _px += other_jet._px;
00193   _py += other_jet._py;
00194   _pz += other_jet._pz;
00195   _E  += other_jet._E ;
00196   _finish_init(); // we need to recalculate phi,rap,kt2  
00197 }

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

subtract the other jet's momentum from this jet

Definition at line 202 of file PseudoJet.cc.

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

00202                                                       {
00203   _px -= other_jet._px;
00204   _py -= other_jet._py;
00205   _pz -= other_jet._pz;
00206   _E  -= other_jet._E ;
00207   _finish_init(); // we need to recalculate phi,rap,kt2  
00208 }

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

divide the jet's momentum by the coefficient

Definition at line 184 of file PseudoJet.cc.

00184                                        {
00185   (*this) *= 1.0/coeff;
00186 }

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

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

Definition at line 100 of file PseudoJet.hh.

00100 { return (*this)(i); }; // this too

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

returns the scalar transverse momentum

Definition at line 94 of file PseudoJet.hh.

Referenced by fastjet::ClusterSequenceActiveArea::_transfer_areas().

00094 {return sqrt(_kt2);};    // like CLHEP

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

returns the squared transverse momentum

Definition at line 92 of file PseudoJet.hh.

Referenced by fastjet::ClusterSequenceActiveArea::_transfer_areas(), fastjet::ClusterSequence::inclusive_jets(), and print_jets().

00092 {return _kt2;};  // like CLHEP

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

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

Definition at line 73 of file PseudoJet.hh.

00073 {return phi_02pi();};

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

returns phi in the range 0..2pi

Definition at line 80 of file PseudoJet.hh.

00080 {return _phi;};

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

returns phi in the range -pi..pi

Definition at line 76 of file PseudoJet.hh.

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

00076                                        {
00077     return _phi > pi ? _phi-twopi : pi;};

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

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

Definition at line 226 of file PseudoJet.cc.

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

00226                                                               {
00227   double dphi = abs(_phi - other._phi);
00228   if (dphi > pi) {dphi = twopi - dphi;}
00229   double drap = _rap - other._rap;
00230   return (dphi*dphi + drap*drap);
00231 }

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

Definition at line 68 of file PseudoJet.hh.

Referenced by _finish_init(), operator()(), fastjet::operator+(), and fastjet::operator-().

00068 {return _px;};

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

Definition at line 69 of file PseudoJet.hh.

Referenced by _finish_init(), operator()(), fastjet::operator+(), and fastjet::operator-().

00069 {return _py;};

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

Definition at line 70 of file PseudoJet.hh.

Referenced by operator()(), fastjet::operator+(), and fastjet::operator-().

00070 {return _pz;};

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

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

Definition at line 84 of file PseudoJet.hh.

Referenced by main().

00084 {return _rap;};

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

the same as rap()

Definition at line 87 of file PseudoJet.hh.

00087 {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 110 of file PseudoJet.hh.

00110 {_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 115 of file PseudoJet.hh.

Referenced by main().

00115 {_user_index = index;};

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

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

Definition at line 113 of file PseudoJet.hh.

00113 {return _user_index;};

Member Data Documentation

int fastjet::PseudoJet::_cluster_hist_index [private]
 

Definition at line 145 of file PseudoJet.hh.

double fastjet::PseudoJet::_E [private]
 

Definition at line 143 of file PseudoJet.hh.

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

double fastjet::PseudoJet::_kt2 [private]
 

Definition at line 144 of file PseudoJet.hh.

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

double fastjet::PseudoJet::_phi [private]
 

Definition at line 144 of file PseudoJet.hh.

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

double fastjet::PseudoJet::_px [private]
 

Definition at line 143 of file PseudoJet.hh.

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

double fastjet::PseudoJet::_py [private]
 

Definition at line 143 of file PseudoJet.hh.

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

double fastjet::PseudoJet::_pz [private]
 

Definition at line 143 of file PseudoJet.hh.

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

double fastjet::PseudoJet::_rap [private]
 

Definition at line 144 of file PseudoJet.hh.

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

int fastjet::PseudoJet::_user_index [private]
 

Definition at line 145 of file PseudoJet.hh.

The documentation for this class was generated from the following files:
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