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TpcSpaceChargeMatrixInversion.cc
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1 
10 
11 #include <frog/FROG.h>
12 
13 #include <TFile.h>
14 #include <TH3.h>
15 
16 #include <Eigen/Core>
17 #include <Eigen/Dense>
18 
19 #include <memory>
20 
21 namespace
22 {
23  // phi range
24  static constexpr float m_phimin = 0;
25  static constexpr float m_phimax = 2.*M_PI;
26 
27  // TODO: could try to get the r and z range from TPC geometry
28  // r range
29  static constexpr float m_rmin = 20;
30  static constexpr float m_rmax = 78;
31 
32  // z range
33  static constexpr float m_zmin = -105.5;
34  static constexpr float m_zmax = 105.5;
35 }
36 
37 //_____________________________________________________________________
39  Fun4AllBase( name)
40 {}
41 
42 //_____________________________________________________________________
45 
46 //_____________________________________________________________________
47 bool TpcSpaceChargeMatrixInversion::add_from_file( const std::string& shortfilename, const std::string& objectname )
48 {
49  // get filename from frog
50  FROG frog;
51  const auto filename = frog.location( shortfilename );
52 
53  // open TFile
54  std::unique_ptr<TFile> inputfile( TFile::Open( filename ) );
55  if( !inputfile )
56  {
57  std::cout << "TpcSpaceChargeMatrixInversion::add_from_file - could not open file " << filename << std::endl;
58  return false;
59  }
60 
61  // load object from input file
62  std::unique_ptr<TpcSpaceChargeMatrixContainer> source( dynamic_cast<TpcSpaceChargeMatrixContainer*>( inputfile->Get( objectname.c_str() ) ) );
63  if( !source )
64  {
65  std::cout << "TpcSpaceChargeMatrixInversion::add_from_file - could not find object name " << objectname << " in file " << filename << std::endl;
66  return false;
67  }
68 
69  // add object
70  return add( *source.get() );
71 }
72 
73 //_____________________________________________________________________
75 {
76  // check internal container, create if necessary
77  if( !m_matrix_container )
78  {
80 
81  // get grid dimensions from source
82  int phibins = 0;
83  int rbins = 0;
84  int zbins = 0;
85  source.get_grid_dimensions( phibins, rbins, zbins );
86 
87  // assign
88  m_matrix_container->set_grid_dimensions( phibins, rbins, zbins );
89  }
90 
91  // add content
92  return m_matrix_container->add( source );
93 }
94 
95 //_____________________________________________________________________
97 {
98 
99  // get grid dimensions from matrix container
100  int phibins = 0;
101  int rbins = 0;
102  int zbins = 0;
103  m_matrix_container->get_grid_dimensions( phibins, rbins, zbins );
104 
105  // create output histograms
106  auto hentries( new TH3F( "hentries_rec", "hentries_rec", phibins, m_phimin, m_phimax, rbins, m_rmin, m_rmax, zbins, m_zmin, m_zmax ) );
107  auto hphi( new TH3F( "hDistortionP_rec", "hDistortionP_rec", phibins, m_phimin, m_phimax, rbins, m_rmin, m_rmax, zbins, m_zmin, m_zmax ) );
108  auto hz( new TH3F( "hDistortionZ_rec", "hDistortionZ_rec", phibins, m_phimin, m_phimax, rbins, m_rmin, m_rmax, zbins, m_zmin, m_zmax ) );
109  auto hr( new TH3F( "hDistortionR_rec", "hDistortionR_rec", phibins, m_phimin, m_phimax, rbins, m_rmin, m_rmax, zbins, m_zmin, m_zmax ) );
110 
111  // set axis labels
112  for( const auto& h:{ hentries, hphi, hz, hr } )
113  {
114  h->GetXaxis()->SetTitle( "#phi (rad)" );
115  h->GetYaxis()->SetTitle( "r (cm)" );
116  h->GetZaxis()->SetTitle( "z (cm)" );
117  }
118 
119  // matrix convenience definition
120  /* number of coordinates must match that of the matrix container */
121  static constexpr int ncoord = 3;
122  using matrix_t = Eigen::Matrix<float, ncoord, ncoord >;
123  using column_t = Eigen::Matrix<float, ncoord, 1 >;
124 
125  // loop over bins
126  for( int iphi = 0; iphi < phibins; ++iphi )
127  for( int ir = 0; ir < rbins; ++ir )
128  for( int iz = 0; iz < zbins; ++iz )
129  {
130 
131  // get cell index
132  const auto icell = m_matrix_container->get_cell_index( iphi, ir, iz );
133 
134  // minimum number of entries per bin
135  static constexpr int min_cluster_count = 2;
136  const auto cell_entries = m_matrix_container->get_entries(icell);
137  if( cell_entries < min_cluster_count ) continue;
138 
139  // build eigen matrices from container
140  matrix_t lhs;
141  for( int i = 0; i < ncoord; ++i )
142  for( int j = 0; j < ncoord; ++j )
143  { lhs(i,j) = m_matrix_container->get_lhs( icell, i, j ); }
144 
145  column_t rhs;
146  for( int i = 0; i < ncoord; ++i )
147  { rhs(i) = m_matrix_container->get_rhs( icell, i ); }
148 
149  if (Verbosity())
150  {
151  // print matrices and entries
152  std::cout << "TpcSpaceChargeMatrixInversion::calculate_distortions - inverting bin " << iz << ", " << ir << ", " << iphi << std::endl;
153  std::cout << "TpcSpaceChargeMatrixInversion::calculate_distortions - entries: " << cell_entries << std::endl;
154  std::cout << "TpcSpaceChargeMatrixInversion::calculate_distortions - lhs: \n" << lhs << std::endl;
155  std::cout << "TpcSpaceChargeMatrixInversion::calculate_distortions - rhs: \n" << rhs << std::endl;
156  }
157 
158  // calculate result using linear solving
159  const auto cov = lhs.inverse();
160  auto partialLu = lhs.partialPivLu();
161  const auto result = partialLu.solve( rhs );
162 
163  // fill histograms
164  hentries->SetBinContent( iphi+1, ir+1, iz+1, cell_entries );
165 
166  hphi->SetBinContent( iphi+1, ir+1, iz+1, result(0) );
167  hphi->SetBinError( iphi+1, ir+1, iz+1, std::sqrt( cov(0,0) ) );
168 
169  hz->SetBinContent( iphi+1, ir+1, iz+1, result(1) );
170  hz->SetBinError( iphi+1, ir+1, iz+1, std::sqrt( cov(1,1) ) );
171 
172  hr->SetBinContent( iphi+1, ir+1, iz+1, result(2) );
173  hr->SetBinError( iphi+1, ir+1, iz+1, std::sqrt( cov(2,2) ) );
174 
175  if (Verbosity())
176  {
177  std::cout << "TpcSpaceChargeMatrixInversion::calculate_distortions - drphi: " << result(0) << " +/- " << std::sqrt( cov(0,0) ) << std::endl;
178  std::cout << "TpcSpaceChargeMatrixInversion::calculate_distortions - dz: " << result(1) << " +/- " << std::sqrt( cov(1,1) ) << std::endl;
179  std::cout << "TpcSpaceChargeMatrixInversion::calculate_distortions - dr: " << result(2) << " +/- " << std::sqrt( cov(2,2) ) << std::endl;
180  std::cout << std::endl;
181  }
182  }
183 
184  // save everything to root file
185  std::cout << "TpcSpaceChargeMatrixInversion::calculate_distortions - writing histograms to " << m_outputfile << std::endl;
186  std::unique_ptr<TFile> outputfile( TFile::Open( m_outputfile.c_str(), "RECREATE" ) );
187  outputfile->cd();
188 
189  // when using migromegas, one needs to extrapolate to the rest of the acceptance
190  if( m_use_micromegas )
191  {
192  for( const auto& h: {hentries, hphi, hr, hz} )
193  {
194  if( !h ) continue;
198  }
199  }
200 
201  // write source histograms
202  for( const auto& h: { hentries, hphi, hr, hz } ) { h->Write(); }
203 
204  // split histograms in two along z axis and write
205  // also write histograms suitable for space charge reconstruction
206  auto process_histogram = []( TH3* h, const TString& name )
207  {
208  TH3* hneg;
209  TH3* hpos;
210  std::tie( hneg, hpos ) = TpcSpaceChargeReconstructionHelper::split( h );
211  hneg->Write();
212  hpos->Write();
214  TpcSpaceChargeReconstructionHelper::copy_histogram( hneg, Form( "%s_negz", name.Data() ) )->Write();
215  TpcSpaceChargeReconstructionHelper::copy_histogram( hpos, Form( "%s_posz", name.Data() ) )->Write();
216  };
217 
218  process_histogram( hentries, "hentries" );
219  process_histogram( hphi, "hIntDistortionP" );
220  process_histogram( hr, "hIntDistortionR" );
221  process_histogram( hz, "hIntDistortionZ" );
222 
223  // close output file
224  outputfile->Close();
225 
226 }