Introduce an enumerator for PID methods
[u/mrichter/AliRoot.git] / TRD / AliTRDseedV1.cxx
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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::RecoParam()->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   AliTRDrecoParam *rec = AliTRDReconstructor::RecoParam();
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::RecoParam()->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::RecoParam()){
359                 AliError("Seed can not be used without a valid RecoParam.");
360                 return kFALSE;
361         }
362
363         AliTRDchamberTimeBin *layer = 0x0;
364         if(AliTRDReconstructor::RecoParam()->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::RecoParam()->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::RecoParam()->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::RecoParam()->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::RecoParam()){
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::RecoParam()->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::RecoParam()->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