JMARKOV::JSphereGenerator Class Reference

Implementation of the JGenerator interface. More...

#include <JMarkovGenerator.hh>

Inheritance diagram for JMARKOV::JSphereGenerator:

Public Member Functions
	JSphereGenerator (const JPosition3D &_x0, double _r=0, TH2 *_h=NULL)
	Constructor. More...
	~JSphereGenerator ()
JPosition3D	getPosition ()
	Return a randomly generated position. More...
double	getWeight (JPosition3D pos)
	return the weight (=probability density dP/dV) for the given position. More...

Public Attributes
JPosition3D	x0
double	r
TH2 *	h

Detailed Description

Implementation of the JGenerator interface.

Generates positions on a sphere of radius _r centered at _x0 by sampling from a 2D histogram of cosTheta vs phi.

When r=0, it simply returns the position x0.

Definition at line 582 of file JMarkovGenerator.hh.

Constructor & Destructor Documentation

JMARKOV::JSphereGenerator::JSphereGenerator ( const JPosition3D &  _x0, double  _r = 0, TH2 *  _h = NULL  )

inline

Constructor.

The histogram is cloned and automatically normalized. The x-axis is assumed to be cos(theta), and the y-axis is assumed to be phi in radians. Empty bins should be avoided!

Definition at line 592 of file JMarkovGenerator.hh.

                                                                          : x0(_x0), r(_r) {
      h = NULL ;

      if( r>0 ) {
        // copy histogram
        h = (TH2*) _h->Clone( _h->GetName() ) ;
        // check that it has the proper limits
        if( h->GetXaxis()->GetXmin()<-1 || h->GetXaxis()->GetXmax()>1 ) {
          cerr << "FATAL ERROR in JSphereGenerator. Invalid x-axis range." << endl ;
          exit(1) ;
        }
        if( h->GetYaxis()->GetXmin() < -M_PI || h->GetYaxis()->GetXmax() > M_PI ) {
          cerr << "FATAL ERROR in JSphereGenerator. Invalid y-axis range." << endl ;
          exit(1) ;
        }
        // normalize histogram
        h->Scale( 1.0/h->Integral("width") ) ;
        h->SetOption("colz") ;
      }
    }

JMARKOV::JSphereGenerator::~JSphereGenerator ( )

inline

Definition at line 613 of file JMarkovGenerator.hh.

                        {
      delete h ;
    }

Member Function Documentation

JPosition3D JMARKOV::JSphereGenerator::getPosition ( )

inlinevirtual

Return a randomly generated position.

Implements JMARKOV::JGenerator.

Definition at line 617 of file JMarkovGenerator.hh.

                              {
      if( r==0 ) return x0 ;

      double costheta, phi ;
      h->GetRandom2(costheta,phi) ;
      return x0 + r * JVector3D(JVersor3D(JAngle3D(acos(costheta),phi))) ;
    }

double JMARKOV::JSphereGenerator::getWeight ( JPosition3D  pos )

inlinevirtual

return the weight (=probability density dP/dV) for the given position.

When the generator is properly normalized, the integral of this quantity over the whole space is 1.

Implements JMARKOV::JGenerator.

Definition at line 625 of file JMarkovGenerator.hh.

                                        {
      if( r==0 ) return 1 ;

      // check that the position is in fact on the target surface
      const double tolerance = 1e-5 ;
      if( fabs( pos.getDistance(x0)-r ) > tolerance*r ) {
        return 0.0 ;
      }

      JVersor3D dir(pos-x0) ;
      double ct = dir.getDZ() ;
      double phi = dir.getPhi() ;

      if( ct < h->GetXaxis()->GetXmin() || ct >=h->GetXaxis()->GetXmax() ) return 0.0 ;
      if( phi< h->GetYaxis()->GetXmin() || phi>=h->GetYaxis()->GetXmax() ) return 0.0 ;

      Int_t bin = h->FindBin(ct,phi) ;
      return h->GetBinContent(bin) / (r*r) ;
    }

Member Data Documentation

JPosition3D JMARKOV::JSphereGenerator::x0

Definition at line 645 of file JMarkovGenerator.hh.

double JMARKOV::JSphereGenerator::r

Definition at line 646 of file JMarkovGenerator.hh.

TH2* JMARKOV::JSphereGenerator::h

Definition at line 647 of file JMarkovGenerator.hh.

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

• JMarkovGenerator.hh