TRD/AliTRDseedV1.cxx

   1 /**************************************************************************
   2  * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
   3  *                                                                        *
   4  * Author: The ALICE Off-line Project.                                    *
   5  * Contributors are mentioned in the code where appropriate.              *
   6  *                                                                        *
   7  * Permission to use, copy, modify and distribute this software and its   *
   8  * documentation strictly for non-commercial purposes is hereby granted   *
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  10  * copies and that both the copyright notice and this permission notice   *
  11  * appear in the supporting documentation. The authors make no claims     *
  12  * about the suitability of this software for any purpose. It is          *
  13  * provided "as is" without express or implied warranty.                  *
  14  **************************************************************************/
  15
  16 /* $Id$ */
  17
  18 ////////////////////////////////////////////////////////////////////////////
  19 //                                                                        //
  20 //  The TRD track seed                                                    //
  21 //                                                                        //
  22 //  Authors:                                                              //
  23 //    Alex Bercuci <A.Bercuci@gsi.de>                                     //
  24 //    Markus Fasel <M.Fasel@gsi.de>                                       //
  25 //                                                                        //
  26 ////////////////////////////////////////////////////////////////////////////
  27
  28 #include "TMath.h"
  29 #include "TLinearFitter.h"
  30 #include "TClonesArray.h" // tmp
  31 #include <TTreeStream.h>
  32
  33 #include "AliLog.h"
  34 #include "AliMathBase.h"
  35
  36 #include "AliTRDcluster.h"
  37 #include "AliTRDseedV1.h"
  38 #include "AliTRDtrackV1.h"
  39 #include "AliTRDcalibDB.h"
  40 #include "AliTRDchamberTimeBin.h"
  41 #include "AliTRDtrackingChamber.h"
  42 #include "AliTRDtrackerV1.h"
  43 #include "AliTRDReconstructor.h"
  44 #include "AliTRDrecoParam.h"
  45 #include "AliTRDgeometry.h"
  46 #include "Cal/AliTRDCalPID.h"
  47
  48 ClassImp(AliTRDseedV1)
  49
  50 //____________________________________________________________________
  51 AliTRDseedV1::AliTRDseedV1(Int_t plane)
  52   :AliTRDseed()
  53   ,fPlane(plane)
  54   ,fMom(0.)
  55   ,fSnp(0.)
  56   ,fTgl(0.)
  57   ,fdX(0.)
  58 {
  59   //
  60   // Constructor
  61   //
  62         for(int islice=0; islice < knSlices; islice++) fdEdx[islice] = 0.;
  63         for(int ispec=0; ispec<AliPID::kSPECIES; ispec++) fProb[ispec]  = -1.;
  64 }
  65
  66 //____________________________________________________________________
  67 AliTRDseedV1::AliTRDseedV1(const AliTRDseedV1 &ref)
  68   :AliTRDseed((AliTRDseed&)ref)
  69   ,fPlane(ref.fPlane)
  70   ,fMom(ref.fMom)
  71   ,fSnp(ref.fSnp)
  72   ,fTgl(ref.fTgl)
  73   ,fdX(ref.fdX)
  74 {
  75   //
  76   // Copy Constructor performing a deep copy
  77   //
  78
  79         //AliInfo("");
  80         for(int islice=0; islice < knSlices; islice++) fdEdx[islice] = ref.fdEdx[islice];
  81         for(int ispec=0; ispec<AliPID::kSPECIES; ispec++) fProb[ispec] = ref.fProb[ispec];
  82 }
  83
  84
  85 //____________________________________________________________________
  86 AliTRDseedV1& AliTRDseedV1::operator=(const AliTRDseedV1 &ref)
  87 {
  88   //
  89   // Assignment Operator using the copy function
  90   //
  91
  92         //AliInfo("");
  93         if(this != &ref){
  94                 ref.Copy(*this);
  95         }
  96         return *this;
  97
  98 }
  99
 100 //____________________________________________________________________
 101 AliTRDseedV1::~AliTRDseedV1()
 102 {
 103   //
 104   // Destructor. The RecoParam object belongs to the underlying tracker.
 105   //
 106
 107         //AliInfo(Form("fOwner[%s]", fOwner?"YES":"NO"));
 108
 109         if(IsOwner())
 110                 for(int itb=0; itb<knTimebins; itb++){
 111                         if(!fClusters[itb]) continue;
 112                         //AliInfo(Form("deleting c %p @ %d", fClusters[itb], itb));
 113                         delete fClusters[itb];
 114                         fClusters[itb] = 0x0;
 115                 }
 116 }
 117
 118 //____________________________________________________________________
 119 void AliTRDseedV1::Copy(TObject &ref) const
 120 {
 121   //
 122   // Copy function
 123   //
 124
 125         //AliInfo("");
 126         AliTRDseedV1 &target = (AliTRDseedV1 &)ref;
 127
 128         target.fPlane         = fPlane;
 129         target.fMom           = fMom;
 130         target.fSnp           = fSnp;
 131         target.fTgl           = fTgl;
 132         target.fdX            = fdX;
 133
 134         for(int islice=0; islice < knSlices; islice++) target.fdEdx[islice] = fdEdx[islice];
 135         for(int ispec=0; ispec<AliPID::kSPECIES; ispec++) target.fProb[ispec] = fProb[ispec];
 136
 137         AliTRDseed::Copy(target);
 138 }
 139
 140
 141 //____________________________________________________________
 142 Bool_t AliTRDseedV1::Init(AliTRDtrackV1 *track)
 143 {
 144 // Initialize this tracklet using the track information
 145 //
 146 // Parameters:
 147 //   track - the TRD track used to initialize the tracklet
 148 //
 149 // Detailed description
 150 // The function sets the starting point and direction of the
 151 // tracklet according to the information from the TRD track.
 152 //
 153 // Caution
 154 // The TRD track has to be propagated to the beginning of the
 155 // chamber where the tracklet will be constructed
 156 //
 157
 158         Double_t y, z;
 159         if(!track->GetProlongation(fX0, y, z)) return kFALSE;
 160         fYref[0] = y;
 161         fYref[1] = track->GetSnp()/(1. - track->GetSnp()*track->GetSnp());
 162         fZref[0] = z;
 163         fZref[1] = track->GetTgl();
 164
 165         //printf("Tracklet ref x[%7.3f] y[%7.3f] z[%7.3f], snp[%f] tgl[%f]\n", fX0, fYref[0], fZref[0], track->GetSnp(), track->GetTgl());
 166         return kTRUE;
 167 }
 168
 169
 170 //____________________________________________________________________
 171 void AliTRDseedV1::CookdEdx(Int_t nslices)
 172 {
 173 // Calculates average dE/dx for all slices and store them in the internal array fdEdx.
 174 //
 175 // Parameters:
 176 //  nslices : number of slices for which dE/dx should be calculated
 177 // Output:
 178 //  store results in the internal array fdEdx. This can be accessed with the method
 179 //  AliTRDseedV1::GetdEdx()
 180 //
 181 // Detailed description
 182 // Calculates average dE/dx for all slices. Depending on the PID methode
 183 // the number of slices can be 3 (LQ) or 8(NN).
 184 // The calculation of dQ/dl are done using the tracklet fit results (see AliTRDseedV1::GetdQdl(Int_t)) i.e.
 185 //
 186 // dQ/dl = qc/(dx * sqrt(1 + dy/dx^2 + dz/dx^2))
 187 //
 188 // The following effects are included in the calculation:
 189 // 1. calibration values for t0 and vdrift (using x coordinate to calculate slice)
 190 // 2. cluster sharing (optional see AliTRDrecoParam::SetClusterSharing())
 191 // 3. cluster size
 192 //
 193
 194         Int_t nclusters[knSlices];
 195         for(int i=0; i<knSlices; i++){
 196                 fdEdx[i]     = 0.;
 197                 nclusters[i] = 0;
 198         }
 199         Float_t clength = (/*.5 * */AliTRDgeometry::AmThick() + AliTRDgeometry::DrThick());
 200
 201         AliTRDcluster *cluster = 0x0;
 202         for(int ic=0; ic<AliTRDtrackerV1::GetNTimeBins(); ic++){
 203                 if(!(cluster = fClusters[ic])) continue;
 204                 Float_t x = cluster->GetX();
 205
 206                 // Filter clusters for dE/dx calculation
 207
 208                 // 1.consider calibration effects for slice determination
 209                 Int_t slice;
 210                 if(cluster->IsInChamber()) slice = Int_t(TMath::Abs(fX0 - x) * nslices / clength);
 211                 else slice = x < fX0 ? 0 : nslices-1;
 212
 213                 // 2. take sharing into account
 214                 Float_t w = cluster->IsShared() ? .5 : 1.;
 215
 216                 // 3. take into account large clusters TODO
 217                 //w *= c->GetNPads() > 3 ? .8 : 1.;
 218
 219                 //CHECK !!!
 220                 fdEdx[slice]   += w * GetdQdl(ic); //fdQdl[ic];
 221                 nclusters[slice]++;
 222         } // End of loop over clusters
 223
 224         if(AliTRDReconstructor::GetRecoParam()->GetPIDMethod() == AliTRDrecoParam::kLQPID){
 225         // calculate mean charge per slice (only LQ PID)
 226                 for(int is=0; is<nslices; is++){
 227             if(nclusters[is]) fdEdx[is] /= nclusters[is];
 228           }
 229         }
 230 }
 231
 232
 233 //____________________________________________________________________
 234 Float_t AliTRDseedV1::GetdQdl(Int_t ic) const
 235 {
 236         return fClusters[ic] ? TMath::Abs(fClusters[ic]->GetQ()) /fdX / TMath::Sqrt(1. + fYfit[1]*fYfit[1] + fZref[1]*fZref[1]) : 0.;
 237 }
 238
 239 //____________________________________________________________________
 240 Double_t* AliTRDseedV1::GetProbability()
 241 {
 242 // Fill probability array for tracklet from the DB.
 243 //
 244 // Parameters
 245 //
 246 // Output
 247 //   returns pointer to the probability array and 0x0 if missing DB access
 248 //
 249 // Detailed description
 250
 251
 252         // retrive calibration db
 253   AliTRDcalibDB *calibration = AliTRDcalibDB::Instance();
 254   if (!calibration) {
 255     AliError("No access to calibration data");
 256     return 0x0;
 257   }
 258
 259   const AliTRDrecoParam *rec = AliTRDReconstructor::GetRecoParam();
 260   if (!rec) {
 261     AliError("No TRD reco param.");
 262     return 0x0;
 263   }
 264
 265   // Retrieve the CDB container class with the parametric detector response
 266   const AliTRDCalPID *pd = calibration->GetPIDObject(rec->GetPIDMethod());
 267   if (!pd) {
 268     AliError("No access to AliTRDCalPID object");
 269     return 0x0;
 270   }
 271         //AliInfo(Form("Method[%d] : %s", AliTRDReconstructor::GetRecoParam()->GetPIDMethod(), pd->IsA()->GetName()));
 272
 273         // calculate tracklet length TO DO
 274   Float_t length = (AliTRDgeometry::AmThick() + AliTRDgeometry::DrThick());
 275   /// TMath::Sqrt((1.0 - fSnp[iPlane]*fSnp[iPlane]) / (1.0 + fTgl[iPlane]*fTgl[iPlane]));
 276
 277   //calculate dE/dx
 278   CookdEdx(rec->GetNdEdxSlices());
 279
 280   // Sets the a priori probabilities
 281   for(int ispec=0; ispec<AliPID::kSPECIES; ispec++) {
 282     fProb[ispec] = pd->GetProbability(ispec, fMom, &fdEdx[0], length, fPlane);
 283   }
 284
 285         return &fProb[0];
 286 }
 287
 288 //____________________________________________________________________
 289 Float_t AliTRDseedV1::GetQuality(Bool_t kZcorr) const
 290 {
 291   //
 292   // Returns a quality measurement of the current seed
 293   //
 294
 295         Float_t zcorr = kZcorr ? fTilt * (fZProb - fZref[0]) : 0.;
 296         return
 297                   .5 * TMath::Abs(18.0 - fN2)
 298                 + 10.* TMath::Abs(fYfit[1] - fYref[1])
 299                 + 5. * TMath::Abs(fYfit[0] - fYref[0] + zcorr)
 300                 + 2. * TMath::Abs(fMeanz - fZref[0]) / fPadLength;
 301 }
 302
 303 //____________________________________________________________________
 304 void AliTRDseedV1::GetCovAt(Double_t /*x*/, Double_t *cov) const
 305 {
 306 // Computes covariance in the y-z plane at radial point x
 307
 308         Int_t ic = 0; while (!fClusters[ic]) ic++;
 309   AliTRDcalibDB *fCalib = AliTRDcalibDB::Instance();
 310         Double_t exB         = fCalib->GetOmegaTau(fCalib->GetVdriftAverage(fClusters[ic]->GetDetector()), -AliTracker::GetBz()*0.1);
 311
 312         Double_t sy2    = fSigmaY2*fSigmaY2 + .2*(fYfit[1]-exB)*(fYfit[1]-exB);
 313         Double_t sz2    = fPadLength/12.;
 314
 315
 316         //printf("Yfit[1] %f sy20 %f SigmaY2 %f\n", fYfit[1], sy20, fSigmaY2);
 317
 318         cov[0] = sy2;
 319         cov[1] = fTilt*(sy2-sz2);
 320         cov[2] = sz2;
 321 }
 322
 323
 324 //____________________________________________________________________
 325 void AliTRDseedV1::SetOwner(Bool_t own)
 326 {
 327         //AliInfo(Form("own [%s] fOwner[%s]", own?"YES":"NO", fOwner?"YES":"NO"));
 328
 329         if(own){
 330                 for(int ic=0; ic<knTimebins; ic++){
 331                         if(!fClusters[ic]) continue;
 332                         fClusters[ic] = new AliTRDcluster(*fClusters[ic]);
 333                 }
 334                 SetBit(1);
 335         } else {
 336                 if(IsOwner()){
 337                         for(int ic=0; ic<knTimebins; ic++){
 338                                 if(!fClusters[ic]) continue;
 339                                 delete fClusters[ic];
 340                                 //fClusters[ic] = tracker->GetClusters(index) TODO
 341                         }
 342                 }
 343                 SetBit(1, kFALSE);
 344         }
 345 }
 346
 347 //____________________________________________________________________
 348 Bool_t  AliTRDseedV1::AttachClustersIter(AliTRDtrackingChamber *chamber, Float_t quality, Bool_t kZcorr, AliTRDcluster *c)
 349 {
 350   //
 351   // Iterative process to register clusters to the seed.
 352   // In iteration 0 we try only one pad-row and if quality not
 353   // sufficient we try 2 pad-rows (about 5% of tracks cross 2 pad-rows)
 354   //
 355         // debug level 7
 356         //
 357
 358         if(!AliTRDReconstructor::GetRecoParam()){
 359                 AliError("Seed can not be used without a valid RecoParam.");
 360                 return kFALSE;
 361         }
 362
 363         AliTRDchamberTimeBin *layer = 0x0;
 364         if(AliTRDReconstructor::GetRecoParam()->GetStreamLevel()>=7 && c){
 365                 TClonesArray clusters("AliTRDcluster", 24);
 366                 clusters.SetOwner(kTRUE);
 367                 AliTRDcluster *cc = 0x0;
 368                 Int_t det=-1, ncl, ncls = 0;
 369                 for (Int_t iTime = 0; iTime < AliTRDtrackerV1::GetNTimeBins(); iTime++) {
 370                         if(!(layer = chamber->GetTB(iTime))) continue;
 371                         if(!(ncl = Int_t(*layer))) continue;
 372                         for(int ic=0; ic<ncl; ic++){
 373                                 cc = (*layer)[ic];
 374                                 det = cc->GetDetector();
 375                                 new(clusters[ncls++]) AliTRDcluster(*cc);
 376                         }
 377                 }
 378                 AliInfo(Form("N clusters[%d] = %d", fPlane, ncls));
 379
 380                 Int_t ref = c ? 1 : 0;
 381                 TTreeSRedirector &cstreamer = *AliTRDtrackerV1::DebugStreamer();
 382                 cstreamer << "AttachClustersIter"
 383                         << "det="        << det
 384                         << "ref="        << ref
 385                         << "clusters.="  << &clusters
 386                         << "tracklet.="  << this
 387                         << "cl.="        << c
 388                         << "\n";
 389         }
 390
 391         Float_t  tquality;
 392         Double_t kroady = AliTRDReconstructor::GetRecoParam()->GetRoad1y();
 393         Double_t kroadz = fPadLength * .5 + 1.;
 394
 395         // initialize configuration parameters
 396         Float_t zcorr = kZcorr ? fTilt * (fZProb - fZref[0]) : 0.;
 397         Int_t   niter = kZcorr ? 1 : 2;
 398
 399         Double_t yexp, zexp;
 400         Int_t ncl = 0;
 401         // start seed update
 402         for (Int_t iter = 0; iter < niter; iter++) {
 403                 ncl = 0;
 404                 for (Int_t iTime = 0; iTime < AliTRDtrackerV1::GetNTimeBins(); iTime++) {
 405                         if(!(layer = chamber->GetTB(iTime))) continue;
 406                         if(!Int_t(*layer)) continue;
 407
 408                         // define searching configuration
 409                         Double_t dxlayer = layer->GetX() - fX0;
 410                         if(c){
 411                                 zexp = c->GetZ();
 412                                 //Try 2 pad-rows in second iteration
 413                                 if (iter > 0) {
 414                                         zexp = fZref[0] + fZref[1] * dxlayer - zcorr;
 415                                         if (zexp > c->GetZ()) zexp = c->GetZ() + fPadLength*0.5;
 416                                         if (zexp < c->GetZ()) zexp = c->GetZ() - fPadLength*0.5;
 417                                 }
 418                         } else zexp = fZref[0] + (kZcorr ? fZref[1] * dxlayer : 0.);
 419                         yexp  = fYref[0] + fYref[1] * dxlayer - zcorr;
 420
 421                         // Get and register cluster
 422                         Int_t    index = layer->SearchNearestCluster(yexp, zexp, kroady, kroadz);
 423                         if (index < 0) continue;
 424                         AliTRDcluster *cl = (*layer)[index];
 425
 426                         fIndexes[iTime]  = layer->GetGlobalIndex(index);
 427                         fClusters[iTime] = cl;
 428                         fY[iTime]        = cl->GetY();
 429                         fZ[iTime]        = cl->GetZ();
 430                         ncl++;
 431                 }
 432         if(AliTRDReconstructor::GetRecoParam()->GetStreamLevel()>=7) AliInfo(Form("iter = %d ncl [%d] = %d", iter, fPlane, ncl));
 433
 434                 if(ncl>1){
 435                         // calculate length of the time bin (calibration aware)
 436                         Int_t irp = 0; Float_t x[2]; Int_t tb[2];
 437                         for (Int_t iTime = 0; iTime < AliTRDtrackerV1::GetNTimeBins(); iTime++) {
 438                                 if(!fClusters[iTime]) continue;
 439                                 x[irp]  = fClusters[iTime]->GetX();
 440                                 tb[irp] = iTime;
 441                                 irp++;
 442                                 if(irp==2) break;
 443                         }
 444                         fdX = (x[1] - x[0]) / (tb[0] - tb[1]);
 445
 446                         // update X0 from the clusters (calibration/alignment aware)
 447                         for (Int_t iTime = 0; iTime < AliTRDtrackerV1::GetNTimeBins(); iTime++) {
 448                                 if(!(layer = chamber->GetTB(iTime))) continue;
 449                                 if(!layer->IsT0()) continue;
 450                                 if(fClusters[iTime]){
 451                                         fX0 = fClusters[iTime]->GetX();
 452                                         break;
 453                                 } else { // we have to infere the position of the anode wire from the other clusters
 454                                         for (Int_t jTime = iTime+1; jTime < AliTRDtrackerV1::GetNTimeBins(); jTime++) {
 455                                                 if(!fClusters[jTime]) continue;
 456                                                 fX0 = fClusters[jTime]->GetX() + fdX * (jTime - iTime);
 457                                         }
 458                                         break;
 459                                 }
 460                         }
 461
 462                         // update YZ reference point
 463                         // TODO
 464
 465                         // update x reference positions (calibration/alignment aware)
 466                         for (Int_t iTime = 0; iTime < AliTRDtrackerV1::GetNTimeBins(); iTime++) {
 467                                 if(!fClusters[iTime]) continue;
 468                                 fX[iTime] = fClusters[iTime]->GetX() - fX0;
 469                         }
 470
 471                         AliTRDseed::Update();
 472                 }
 473         if(AliTRDReconstructor::GetRecoParam()->GetStreamLevel()>=7) AliInfo(Form("iter = %d nclFit [%d] = %d", iter, fPlane, fN2));
 474
 475                 if(IsOK()){
 476                         tquality = GetQuality(kZcorr);
 477                         if(tquality < quality) break;
 478                         else quality = tquality;
 479                 }
 480                 kroadz *= 2.;
 481         } // Loop: iter
 482         if (!IsOK()) return kFALSE;
 483
 484         CookLabels();
 485         UpdateUsed();
 486         return kTRUE;
 487 }
 488
 489 //____________________________________________________________________
 490 Bool_t  AliTRDseedV1::AttachClusters(AliTRDtrackingChamber *chamber
 491                                        ,Bool_t kZcorr)
 492 {
 493   //
 494   // Projective algorithm to attach clusters to seeding tracklets
 495   //
 496   // Parameters
 497   //
 498   // Output
 499   //
 500   // Detailed description
 501   // 1. Collapse x coordinate for the full detector plane
 502   // 2. truncated mean on y (r-phi) direction
 503   // 3. purge clusters
 504   // 4. truncated mean on z direction
 505   // 5. purge clusters
 506   // 6. fit tracklet
 507   //
 508
 509         if(!AliTRDReconstructor::GetRecoParam()){
 510                 AliError("Seed can not be used without a valid RecoParam.");
 511                 return kFALSE;
 512         }
 513
 514         const Int_t kClusterCandidates = 2 * knTimebins;
 515
 516         //define roads
 517         Double_t kroady = AliTRDReconstructor::GetRecoParam()->GetRoad1y();
 518         Double_t kroadz = fPadLength * 1.5 + 1.;
 519         // correction to y for the tilting angle
 520         Float_t zcorr = kZcorr ? fTilt * (fZProb - fZref[0]) : 0.;
 521
 522         // working variables
 523         AliTRDcluster *clusters[kClusterCandidates];
 524         Double_t cond[4], yexp[knTimebins], zexp[knTimebins],
 525                 yres[kClusterCandidates], zres[kClusterCandidates];
 526         Int_t ncl, *index = 0x0, tboundary[knTimebins];
 527
 528         // Do cluster projection
 529         AliTRDchamberTimeBin *layer = 0x0;
 530         Int_t nYclusters = 0; Bool_t kEXIT = kFALSE;
 531         for (Int_t iTime = 0; iTime < AliTRDtrackerV1::GetNTimeBins(); iTime++) {
 532                 if(!(layer = chamber->GetTB(iTime))) continue;
 533                 if(!Int_t(*layer)) continue;
 534
 535                 fX[iTime] = layer->GetX() - fX0;
 536                 zexp[iTime] = fZref[0] + fZref[1] * fX[iTime];
 537                 yexp[iTime] = fYref[0] + fYref[1] * fX[iTime] - zcorr;
 538
 539                 // build condition and process clusters
 540                 cond[0] = yexp[iTime] - kroady; cond[1] = yexp[iTime] + kroady;
 541                 cond[2] = zexp[iTime] - kroadz; cond[3] = zexp[iTime] + kroadz;
 542                 layer->GetClusters(cond, index, ncl);
 543                 for(Int_t ic = 0; ic<ncl; ic++){
 544                         AliTRDcluster *c = layer->GetCluster(index[ic]);
 545                         clusters[nYclusters] = c;
 546                         yres[nYclusters++] = c->GetY() - yexp[iTime];
 547                         if(nYclusters >= kClusterCandidates) {
 548                                 AliWarning(Form("Cluster candidates reached limit %d. Some may be lost.", kClusterCandidates));
 549                                 kEXIT = kTRUE;
 550                                 break;
 551                         }
 552                 }
 553                 tboundary[iTime] = nYclusters;
 554                 if(kEXIT) break;
 555         }
 556
 557         // Evaluate truncated mean on the y direction
 558         Double_t mean, sigma;
 559         AliMathBase::EvaluateUni(nYclusters, yres, mean, sigma, Int_t(nYclusters*.8)-2);
 560         // purge cluster candidates
 561         Int_t nZclusters = 0;
 562         for(Int_t ic = 0; ic<nYclusters; ic++){
 563                 if(yres[ic] - mean > 4. * sigma){
 564                         clusters[ic] = 0x0;
 565                         continue;
 566                 }
 567                 zres[nZclusters++] = clusters[ic]->GetZ() - zexp[clusters[ic]->GetLocalTimeBin()];
 568         }
 569
 570         // Evaluate truncated mean on the z direction
 571         AliMathBase::EvaluateUni(nZclusters, zres, mean, sigma, Int_t(nZclusters*.8)-2);
 572         // purge cluster candidates
 573         for(Int_t ic = 0; ic<nZclusters; ic++){
 574                 if(zres[ic] - mean > 4. * sigma){
 575                         clusters[ic] = 0x0;
 576                         continue;
 577                 }
 578         }
 579
 580
 581         // Select only one cluster/TimeBin
 582         Int_t lastCluster = 0;
 583         fN2 = 0;
 584         for (Int_t iTime = 0; iTime < AliTRDtrackerV1::GetNTimeBins(); iTime++) {
 585                 ncl = tboundary[iTime] - lastCluster;
 586                 if(!ncl) continue;
 587                 Int_t iptr = lastCluster;
 588                 if(ncl > 1){
 589                         Float_t dold = 9999.;
 590                         for(int ic=lastCluster; ic<tboundary[iTime]; ic++){
 591                                 if(!clusters[ic]) continue;
 592                                 Float_t y = yexp[iTime] - clusters[ic]->GetY();
 593                                 Float_t z = zexp[iTime] - clusters[ic]->GetZ();
 594                                 Float_t d = y * y + z * z;
 595                                 if(d > dold) continue;
 596                                 dold = d;
 597                                 iptr = ic;
 598                         }
 599                 }
 600                 fIndexes[iTime]  = chamber->GetTB(iTime)->GetGlobalIndex(iptr);
 601                 fClusters[iTime] = clusters[iptr];
 602                 fY[iTime]        = clusters[iptr]->GetY();
 603                 fZ[iTime]        = clusters[iptr]->GetZ();
 604                 lastCluster      = tboundary[iTime];
 605                 fN2++;
 606         }
 607
 608         // number of minimum numbers of clusters expected for the tracklet
 609         Int_t kClmin = Int_t(AliTRDReconstructor::GetRecoParam()->GetFindableClusters()*AliTRDtrackerV1::GetNTimeBins());
 610   if (fN2 < kClmin){
 611                 AliWarning(Form("Not enough clusters to fit the tracklet %d [%d].", fN2, kClmin));
 612     fN2 = 0;
 613     return kFALSE;
 614   }
 615
 616         // update used clusters
 617         fNUsed = 0;
 618         for (Int_t iTime = 0; iTime < AliTRDtrackerV1::GetNTimeBins(); iTime++) {
 619                 if(!fClusters[iTime]) continue;
 620                 if((fClusters[iTime]->IsUsed())) fNUsed++;
 621         }
 622
 623   if (fN2-fNUsed < kClmin){
 624                 AliWarning(Form("Too many clusters already in use %d (from %d).", fNUsed, fN2));
 625     fN2 = 0;
 626     return kFALSE;
 627   }
 628
 629         return kTRUE;
 630 }
 631
 632 //____________________________________________________________________
 633 Bool_t AliTRDseedV1::Fit()
 634 {
 635   //
 636   // Linear fit of the tracklet
 637   //
 638   // Parameters :
 639   //
 640   // Output :
 641   //  True if successful
 642   //
 643   // Detailed description
 644   // 2. Check if tracklet crosses pad row boundary
 645   // 1. Calculate residuals in the y (r-phi) direction
 646   // 3. Do a Least Square Fit to the data
 647   //
 648
 649         const Int_t kClmin = 8;
 650         const Int_t kNtb = AliTRDtrackerV1::GetNTimeBins();
 651         AliTRDtrackerV1::AliTRDLeastSquare fitterY, fitterZ;
 652
 653         // convertion factor from square to gauss distribution for sigma
 654         Double_t convert = 1./TMath::Sqrt(12.);
 655
 656         // book cluster information
 657         Double_t xc[knTimebins+1], yc[knTimebins], zc[knTimebins+1], sy[knTimebins], sz[knTimebins+1];
 658         Int_t zRow[knTimebins];
 659         AliTRDcluster *c = 0x0;
 660         Int_t nc = 0;
 661         for (Int_t ic=0; ic<kNtb; ic++) {
 662                 zRow[ic] = -1;
 663                 xc[ic]  = -1.;
 664                 yc[ic]  = 999.;
 665                 zc[ic]  = 999.;
 666                 sy[ic]  = 0.;
 667                 sz[ic]  = 0.;
 668                 if(!(c = fClusters[ic])) continue;
 669                 if(!c->IsInChamber()) continue;
 670                 Float_t w = 1.;
 671                 if(c->GetNPads()>4) w = .5;
 672                 if(c->GetNPads()>5) w = .2;
 673                 zRow[nc] = c->GetPadRow();
 674                 xc[nc]   = fX0 - c->GetX();
 675                 yc[nc]   = c->GetY();
 676                 zc[nc]   = c->GetZ();
 677                 sy[ic]   = w; // all clusters have the same sigma
 678                 sz[ic]   = fPadLength*convert;
 679                 fitterZ.AddPoint(&xc[ic], zc[ic], sz[ic]);
 680                 nc++;
 681         }
 682   // to few clusters
 683         if (nc < kClmin) return kFALSE;
 684
 685
 686         Int_t zN[2*35];
 687   Int_t nz = AliTRDtrackerV1::Freq(nc, zRow, zN, kFALSE);
 688         // more than one pad row crossing
 689         if(nz>2) return kFALSE;
 690
 691         // estimate reference parameter at average x
 692         Double_t y0 = fYref[0];
 693         Double_t dydx = fYref[1];
 694         Double_t dzdx = fZref[1];
 695         zc[nc]  = fZref[0];
 696
 697         // determine z offset of the fit
 698         Int_t nchanges = 0, nCross = 0;
 699         if(nz==2){ // tracklet is crossing pad row
 700                 // Find the break time allowing one chage on pad-rows
 701                 // with maximal number of accepted clusters
 702                 Int_t padRef = zRow[0];
 703                 for (Int_t ic=1; ic<nc; ic++) {
 704                         if(zRow[ic] == padRef) continue;
 705
 706                         // debug
 707                         if(zRow[ic-1] == zRow[ic]){
 708                                 printf("ERROR in pad row change!!!\n");
 709                         }
 710
 711                         // evaluate parameters of the crossing point
 712                         Float_t sx = (xc[ic-1] - xc[ic])*convert;
 713                         xc[nc] = .5 * (xc[ic-1] + xc[ic]);
 714                         zc[nc] = .5 * (zc[ic-1] + zc[ic]);
 715                         sz[nc] = TMath::Max(dzdx * sx, .01);
 716                         dzdx   = zc[ic-1] > zc[ic] ? 1. : -1.;
 717                         padRef = zRow[ic];
 718                         nCross = ic;
 719                         nchanges++;
 720                 }
 721         }
 722
 723         // condition on nCross and reset nchanges TODO
 724
 725         if(nchanges==1){
 726                 if(dzdx * fZref[1] < 0.){
 727                         AliInfo("tracklet direction does not correspond to the track direction. TODO.");
 728                 }
 729                 SetBit(2, kTRUE); // mark pad row crossing
 730                 fCross[0] = xc[nc]; fCross[2] = zc[nc]; fCross[3] = sz[nc];
 731                 fitterZ.AddPoint(&xc[nc], zc[nc], sz[nc]);
 732                 fitterZ.Eval();
 733                 dzdx = fZref[1]; // we don't trust Parameter[1] ??;
 734                 zc[nc] = fitterZ.GetFunctionParameter(0);
 735         } else if(nchanges > 1){ // debug
 736                 AliInfo("ERROR in n changes!!!");
 737                 return kFALSE;
 738         }
 739
 740
 741         // estimate deviation from reference direction
 742         dzdx *= fTilt;
 743         for (Int_t ic=0; ic<nc; ic++) {
 744                 yc[ic] -= y0 + xc[ic]*(dydx + dzdx) + fTilt * (zc[ic] - zc[nc]);
 745                 fitterY.AddPoint(&xc[ic], yc[ic], sy[ic]);
 746         }
 747         fitterY.Eval();
 748         fYfit[0] = y0+fitterY.GetFunctionParameter(0);
 749         fYfit[1] = dydx+fitterY.GetFunctionParameter(1);
 750         if(nchanges) fCross[1] = fYfit[0] + fCross[0] * fYfit[1];
 751
 752 //      printf("\nnz = %d\n", nz);
 753 //      for(int ic=0; ic<35; ic++) printf("%d row[%d]\n", ic, zRow[ic]);
 754 //
 755 //      for(int ic=0; ic<nz; ic++) printf("%d n[%d]\n", ic, zN[ic]);
 756
 757         return kTRUE;
 758 }
 759
 760 //___________________________________________________________________
 761 void AliTRDseedV1::Draw(Option_t*)
 762 {
 763 }
 764
 765 //___________________________________________________________________
 766 void AliTRDseedV1::Print(Option_t*) const
 767 {
 768   //
 769   // Printing the seedstatus
 770   //
 771
 772         printf("Seed status :\n");
 773         printf("  fTilt      = %f\n", fTilt);
 774         printf("  fPadLength = %f\n", fPadLength);
 775         printf("  fX0        = %f\n", fX0);
 776         for(int ic=0; ic<AliTRDtrackerV1::GetNTimeBins(); ic++) {
 777           const Char_t *isUsable = fUsable[ic]?"Yes":"No";
 778           printf("  %d X[%f] Y[%f] Z[%f] Indexes[%d] clusters[%p] usable[%s]\n"
 779                 , ic
 780                 , fX[ic]
 781                 , fY[ic]
 782                 , fZ[ic]
 783                 , fIndexes[ic]
 784                 , ((void*) fClusters[ic])
 785                 , isUsable);
 786         }
 787
 788         printf("  fYref[0] =%f fYref[1] =%f\n", fYref[0], fYref[1]);
 789         printf("  fZref[0] =%f fZref[1] =%f\n", fZref[0], fZref[1]);
 790         printf("  fYfit[0] =%f fYfit[1] =%f\n", fYfit[0], fYfit[1]);
 791         printf("  fYfitR[0]=%f fYfitR[1]=%f\n", fYfitR[0], fYfitR[1]);
 792         printf("  fZfit[0] =%f fZfit[1] =%f\n", fZfit[0], fZfit[1]);
 793         printf("  fZfitR[0]=%f fZfitR[1]=%f\n", fZfitR[0], fZfitR[1]);
 794         printf("  fSigmaY =%f\n", fSigmaY);
 795         printf("  fSigmaY2=%f\n", fSigmaY2);
 796         printf("  fMeanz  =%f\n", fMeanz);
 797         printf("  fZProb  =%f\n", fZProb);
 798         printf("  fLabels[0]=%d fLabels[1]=%d\n", fLabels[0], fLabels[1]);
 799         printf("  fN      =%d\n", fN);
 800         printf("  fN2     =%d (>8 isOK)\n",fN2);
 801         printf("  fNUsed  =%d\n", fNUsed);
 802         printf("  fFreq   =%d\n", fFreq);
 803         printf("  fNChange=%d\n",  fNChange);
 804         printf("  fMPads  =%f\n", fMPads);
 805
 806         printf("  fC      =%f\n", fC);
 807         printf("  fCC     =%f\n",fCC);
 808         printf("  fChi2   =%f\n", fChi2);
 809         printf("  fChi2Z  =%f\n", fChi2Z);
 810 }
 811