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JMARKOV::JMarkovEnsembleIntegrator Class Referenceabstract

Abstract base class for implementations of the JMarkovIntegrator interface, where the sample distribution is based on histograms filled from an ensemble of representative paths. More...

#include <JMarkovIntegrator.hh>

Inheritance diagram for JMARKOV::JMarkovEnsembleIntegrator:
JMARKOV::JMarkovIntegrator JMARKOV::JMarkovEnsembleIntegrator1D JMARKOV::JMarkovEnsembleIntegrator3D

Public Member Functions

 JMarkovEnsembleIntegrator (const vector< JPhotonPath > &_ensemble, JTargetModel *_trg, int _nbinsx, int _nbinsy, int _nbinsz)
 
virtual ~JMarkovEnsembleIntegrator ()
 
virtual void writeHistograms ()=0
 write the histograms filled from the ensemble
 
vector< double > integrate (int N, int nscat, JSourceModel *src, JScatteringModel *sm, JTargetModel *trg, double lambda_abs)
 Integrate with N samples.
 
vector< double > dummy_integrate (int N, int nscat, JSourceModel *src, JScatteringModel *sm, JTargetModel *trg, double lambda_abs)
 Integrate a test function with N samples.
 
vector< JPhotonPathget_diagnostic_ensemble (int N, int nscat, JSourceModel *src, JScatteringModel *sm, JTargetModel *trg, double lambda_abs)
 Return photon paths generated with the generatePath method.
 

Protected Member Functions

JPosition3D generatePosition (int nscat, int nv, double &winv)
 generate a position for vertex nv for the given number of scatterings, winv will be set to 1/weight
 
virtual JPosition3D generateScatteringVertexPosition (int nscat, int nv, double &winv)=0
 
int getIndex (int nv, int nscat)
 return the internal index for a given number of scatterings and vertex number
 
void initgenerators (int nscat)
 initialize the position generators for a given number of scatterings (i.e. create histograms and fill them from the ensemble)
 
void init_target_generator (int nscat)
 initialize the generator for a target vertex for a given number of scatterings
 
virtual void init_scattering_vertex_generators (int nscat)=0
 
void free_target_gens ()
 
virtual JPhotonPath generatePath (int nscat, double &winv)
 Generate a random photon path with a given number of scatterings.
 

Protected Attributes

vector< JSphereGenerator * > target_gens
 
vector< JPhotonPathensemble
 
int nbinsx
 
int nbinsy
 
int nbinsz
 
JTargetModeltrg
 
JPosition3D source_position
 

Detailed Description

Abstract base class for implementations of the JMarkovIntegrator interface, where the sample distribution is based on histograms filled from an ensemble of representative paths.

Definition at line 198 of file JMarkovIntegrator.hh.

Constructor & Destructor Documentation

◆ JMarkovEnsembleIntegrator()

JMARKOV::JMarkovEnsembleIntegrator::JMarkovEnsembleIntegrator ( const vector< JPhotonPath > & _ensemble,
JTargetModel * _trg,
int _nbinsx,
int _nbinsy,
int _nbinsz )
inline

Definition at line 202 of file JMarkovIntegrator.hh.

202 : ensemble(_ensemble), nbinsx(_nbinsx), nbinsy(_nbinsy), nbinsz(_nbinsz), trg(_trg) {
203 // check that the ensemble size is at least one photon path
204 if( ensemble.size()==0 ) {
205 cerr << "FATAL ERROR in JMarkov3DensembleIntegrator constructor. Ensemble size = 0." << endl ;
206 exit(1) ;
207 }
208
209 // check that the position of the first vertex is the same throughout the ensemble
210 for( vector<JPhotonPath>::iterator it=ensemble.begin(); it!=ensemble.end(); ++it ) {
211 if( (*it)[0].getDistance(ensemble.front()[0]) > 0 ) {
212 cerr << "Fatal error in JMarkovEnsembleIntegrator, first vertex positions are not all the same." << endl ;
213 exit(1) ;
214 }
215 }
216 // set source position based on ensemble
217 source_position = ensemble.front()[0] ;
218 }

◆ ~JMarkovEnsembleIntegrator()

virtual JMARKOV::JMarkovEnsembleIntegrator::~JMarkovEnsembleIntegrator ( )
inlinevirtual

Definition at line 220 of file JMarkovIntegrator.hh.

220{} ;

Member Function Documentation

◆ writeHistograms()

virtual void JMARKOV::JMarkovEnsembleIntegrator::writeHistograms ( )
pure virtual

write the histograms filled from the ensemble

Implemented in JMARKOV::JMarkovEnsembleIntegrator1D, and JMARKOV::JMarkovEnsembleIntegrator3D.

◆ generatePosition()

JPosition3D JMARKOV::JMarkovEnsembleIntegrator::generatePosition ( int nscat,
int nv,
double & winv )
inlineprotectedvirtual

generate a position for vertex nv for the given number of scatterings, winv will be set to 1/weight

Implements JMARKOV::JMarkovIntegrator.

Definition at line 228 of file JMarkovIntegrator.hh.

228 {
229 // source vertex
230 if( nv==0 ) {
231 winv = 1.0 ;
232 return source_position ;
233 }
234 // target vertex
235 if( nv == nscat+1 ) {
236 if( nscat+1>(int)target_gens.size() || target_gens[nscat] == NULL ) {
237 initgenerators(nscat) ;
238 }
239 JPosition3D pos = target_gens[nscat]->getPosition() ;
240 winv = 1.0/target_gens[nscat]->getWeight(pos) ;
241 return pos ;
242 } else {
243 // scattering vertex
244 return generateScatteringVertexPosition(nscat,nv,winv) ;
245 }
246 }
virtual JPosition3D generateScatteringVertexPosition(int nscat, int nv, double &winv)=0
void initgenerators(int nscat)
initialize the position generators for a given number of scatterings (i.e. create histograms and fill...
vector< JSphereGenerator * > target_gens

◆ generateScatteringVertexPosition()

virtual JPosition3D JMARKOV::JMarkovEnsembleIntegrator::generateScatteringVertexPosition ( int nscat,
int nv,
double & winv )
protectedpure virtual

◆ getIndex()

int JMARKOV::JMarkovEnsembleIntegrator::getIndex ( int nv,
int nscat )
inlineprotected

return the internal index for a given number of scatterings and vertex number

Definition at line 251 of file JMarkovIntegrator.hh.

251 {
252 // indices are distributed as follows
253 // [0]: nscat=1, nv=1
254 // [1]: nscat=2, nv=1
255 // [2]: nscat=2, nv=2
256 // [3]: nscat=3, nv=1
257 // [4]: nscat=3, nv=2
258 // etc.
259 return (nscat*(nscat-1))/2 + nv - 1 ;
260 }

◆ initgenerators()

void JMARKOV::JMarkovEnsembleIntegrator::initgenerators ( int nscat)
inlineprotected

initialize the position generators for a given number of scatterings (i.e. create histograms and fill them from the ensemble)

Definition at line 263 of file JMarkovIntegrator.hh.

263 {
264 // target vertex
265 init_target_generator(nscat) ;
266
267 // scattering vertices
269 }
virtual void init_scattering_vertex_generators(int nscat)=0
void init_target_generator(int nscat)
initialize the generator for a target vertex for a given number of scatterings

◆ init_target_generator()

void JMARKOV::JMarkovEnsembleIntegrator::init_target_generator ( int nscat)
inlineprotected

initialize the generator for a target vertex for a given number of scatterings

Definition at line 272 of file JMarkovIntegrator.hh.

272 {
273 if( (int)target_gens.size() <= nscat ) target_gens.resize( nscat+1 ) ;
274
275 if( trg->getRadius()>0 ) {
276 // for a finite target, we fill a "sphere generator" from the ensemble
277 char hname[200] ;
278 sprintf( hname, "htarget_nscat%i", nscat ) ;
279 TH2D* ht = new TH2D(hname,";cos(#theta);#phi",100,-1,1,100,-M_PI,M_PI) ;
280 for( vector<JPhotonPath>::iterator it=ensemble.begin() ; it!=ensemble.end() ; ++it ) {
281 if( it->n-2 != nscat ) continue ;
282 JDirection3D dir( it->back() - trg->getPosition() ) ;
283 ht->Fill( dir.getDZ(), dir.getPhi() ) ;
284 }
285 target_gens[nscat] = new JSphereGenerator( trg->getPosition(), trg->getRadius(), ht ) ;
286 delete ht ;
287 } else {
288 // for an infinitesimal target, we create a "generator" that only generates the single point
289 target_gens[nscat] = new JSphereGenerator( trg->getPosition() ) ;
290 }
291 }
const JPosition3D & getPosition() const

◆ init_scattering_vertex_generators()

virtual void JMARKOV::JMarkovEnsembleIntegrator::init_scattering_vertex_generators ( int nscat)
protectedpure virtual

◆ free_target_gens()

void JMARKOV::JMarkovEnsembleIntegrator::free_target_gens ( )
inlineprotected

Definition at line 295 of file JMarkovIntegrator.hh.

295 {
296 for( vector<JSphereGenerator*>::iterator it=target_gens.begin() ; it!=target_gens.end() ; ++it ) {
297 if( *it != NULL ) delete *it ;
298 }
299 }

◆ integrate()

vector< double > JMARKOV::JMarkovIntegrator::integrate ( int N,
int nscat,
JSourceModel * src,
JScatteringModel * sm,
JTargetModel * trg,
double lambda_abs )
inherited

Integrate with N samples.

Returns a vector with the contribution to the integral of each sample. The mean of those values is the estimate of the result of the integral, while the distribution itself can be used to estimate the stability of the result. In this distribution, you want to avoid

  • long tails (because they make the result unstable)
  • small contributions (because it means that parts of the parameter space are being oversampled, so it is less efficient) This can be achieved by tuning the sample distribution to the problem at hand.

Definition at line 130 of file JMarkovIntegrator.hh.

130 {
131 vector<double> contributions(N,-1) ;
132
133 for( int i=0 ; i<N ; ++i ) {
134 double winv ;
135 JPhotonPath p = generatePath(nscat,winv) ;
136
137 double rho = getPhotonPathProbabilityDensity(p,src,sm,trg,lambda_abs) ;
138 contributions[i] = rho * winv ;
139 }
140 return contributions ;
141 }
virtual JPhotonPath generatePath(int nscat, double &winv)
Generate a random photon path with a given number of scatterings.
double getPhotonPathProbabilityDensity(JPhotonPath &p, JSourceModel *src, JScatteringModel *sm, JTargetModel *trg, double lambda_abs)
Return the probability density for a photon path with the given ingredients.

◆ dummy_integrate()

vector< double > JMARKOV::JMarkovIntegrator::dummy_integrate ( int N,
int nscat,
JSourceModel * src,
JScatteringModel * sm,
JTargetModel * trg,
double lambda_abs )
inherited

Integrate a test function with N samples.

This can be used as a sanity check for derived classes of JMarkovIntegrator.

The integral should yield 1 when the complete relevant part of the volume is taken into account. If it does not, it may be a sign that the implementation is not correct.

Returns a vector with the contribution to the integral of each sample.

Definition at line 143 of file JMarkovIntegrator.hh.

143 {
144 vector<double> contributions(N,-1) ;
145
146 for( int i=0 ; i<N ; ++i ) {
147 const double r = 10 ;
148 double winv ;
149 JPhotonPath p = generatePath(nscat,winv) ;
150 double rho = 1.0/(4.0/3.0*M_PI*r*r*r) ;
151 if( p[1].getLength()>r ) rho = 0 ;
152 contributions[i] = rho * winv ;
153 }
154 return contributions ;
155 }

◆ get_diagnostic_ensemble()

vector< JPhotonPath > JMARKOV::JMarkovIntegrator::get_diagnostic_ensemble ( int N,
int nscat,
JSourceModel * src,
JScatteringModel * sm,
JTargetModel * trg,
double lambda_abs )
inherited

Return photon paths generated with the generatePath method.

This can be used to identify the parts of parameter space that are over- or undersampled in a given problem so that the integrator may be optimized to handle those better.

Definition at line 157 of file JMarkovIntegrator.hh.

157 {
158 vector<JPhotonPath> paths ;
159
160 for( int i=0 ; i<N ; ++i ) {
161 double winv ;
162 JPhotonPath p = generatePath(nscat,winv) ;
163 paths.push_back(p) ;
164 }
165 return paths ;
166 }

◆ generatePath()

virtual JPhotonPath JMARKOV::JMarkovIntegrator::generatePath ( int nscat,
double & winv )
inlineprotectedvirtualinherited

Generate a random photon path with a given number of scatterings.

winv must be set to the inverted probability density to generate this particular path.

Definition at line 94 of file JMarkovIntegrator.hh.

94 {
95 // this default implementation assumes that the vertex positions
96 // are completely uncorrelated
97 JPhotonPath p(nscat) ;
98 double _winv = 1 ;
99 for( int nv=0 ; nv<nscat+2 ; ++nv ) {
100 double part_winv ;
101 p[nv] = generatePosition( nscat, nv, part_winv ) ;
102 _winv *= part_winv ;
103 }
104 winv = _winv ;
105 return p ;
106 }
virtual JPosition3D generatePosition(int nscat, int nv, double &winv)=0
Generate a random position for vertex nv.

Member Data Documentation

◆ target_gens

vector<JSphereGenerator*> JMARKOV::JMarkovEnsembleIntegrator::target_gens
protected

Definition at line 301 of file JMarkovIntegrator.hh.

◆ ensemble

vector<JPhotonPath> JMARKOV::JMarkovEnsembleIntegrator::ensemble
protected

Definition at line 302 of file JMarkovIntegrator.hh.

◆ nbinsx

int JMARKOV::JMarkovEnsembleIntegrator::nbinsx
protected

Definition at line 303 of file JMarkovIntegrator.hh.

◆ nbinsy

int JMARKOV::JMarkovEnsembleIntegrator::nbinsy
protected

Definition at line 304 of file JMarkovIntegrator.hh.

◆ nbinsz

int JMARKOV::JMarkovEnsembleIntegrator::nbinsz
protected

Definition at line 305 of file JMarkovIntegrator.hh.

◆ trg

JTargetModel* JMARKOV::JMarkovEnsembleIntegrator::trg
protected

Definition at line 306 of file JMarkovIntegrator.hh.

◆ source_position

JPosition3D JMARKOV::JMarkovEnsembleIntegrator::source_position
protected

Definition at line 307 of file JMarkovIntegrator.hh.


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