1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
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 // **************************************************************************//
17 // * The package was revised and changed by Boris Batiounia in the time //
18 // * period of March - June 2001 //
19 // **************************************************************************//
20 ///////////////////////////////////////////////////////////////////////////////
22 #include <Riostream.h>
26 #include "AliITSClusterFinderSSD.h"
27 #include "AliITSMapA1.h"
28 #include "AliITSRawClusterSSD.h"
29 #include "AliITSRecPoint.h"
30 #include "AliITSclusterSSD.h"
31 #include "AliITSdigitSSD.h"
32 #include "AliITSgeom.h"
33 #include "AliITSpackageSSD.h"
34 #include "AliITSresponseSSD.h"
35 #include "AliITSsegmentationSSD.h"
39 const Bool_t AliITSClusterFinderSSD::fgkSIDEP=kTRUE;
40 const Bool_t AliITSClusterFinderSSD::fgkSIDEN=kFALSE;
42 ClassImp(AliITSClusterFinderSSD)
44 //____________________________________________________________________
47 //______________________________________________________________________
48 AliITSClusterFinderSSD::AliITSClusterFinderSSD():
49 AliITSClusterFinder(),
68 //______________________________________________________________________
69 AliITSClusterFinderSSD::AliITSClusterFinderSSD(AliITSsegmentation *seg,
70 TClonesArray *digits):
71 AliITSClusterFinder(seg,0),
88 //Standard constructor
91 SetMap(new AliITSMapA1(GetSeg(),Digits()));
92 fClusterP = new TClonesArray ("AliITSclusterSSD",200);
94 fClusterN = new TClonesArray ("AliITSclusterSSD",200);
96 fPackages = new TClonesArray ("AliITSpackageSSD",200); //packages
98 fDigitsIndexP = new TArrayI(300);
100 fDigitsIndexN = new TArrayI(300);
102 fPitch = GetSeg()->Dpx(0);
103 fPNsignalRatio= 7./8.; // warning: hard-wired number
105 //______________________________________________________________________}
106 AliITSClusterFinderSSD::AliITSClusterFinderSSD(AliITSsegmentation *seg,
107 AliITSresponse *res):
108 AliITSClusterFinder(seg,res),
125 //Standard constructor
127 fClusterP = new TClonesArray ("AliITSclusterSSD",200);
129 fClusterN = new TClonesArray ("AliITSclusterSSD",200);
131 fPackages = new TClonesArray ("AliITSpackageSSD",200); //packages
133 fDigitsIndexP = new TArrayI(300);
135 fDigitsIndexN = new TArrayI(300);
137 fPitch = GetSeg()->Dpx(0);
138 fPNsignalRatio= 7./8.; // warning: hard-wired number
141 //______________________________________________________________________
142 AliITSClusterFinderSSD::AliITSClusterFinderSSD(const AliITSClusterFinderSSD &source) : AliITSClusterFinder(source) {
144 // Copies are not allowed. The method is protected to avoid misuse.
145 Fatal("AliITSClusterFinderSSD","Copy constructor not allowed\n");
148 //______________________________________________________________________
149 AliITSClusterFinderSSD& AliITSClusterFinderSSD::operator=(const AliITSClusterFinderSSD& /* source */){
150 // Assignment operator
151 // Assignment is not allowed. The method is protected to avoid misuse.
152 Fatal("= operator","Assignment operator not allowed\n");
156 //______________________________________________________________________
157 AliITSClusterFinderSSD::~AliITSClusterFinderSSD(){
158 // Default destructor
163 delete fDigitsIndexP;
164 delete fDigitsIndexN;
166 //______________________________________________________________________
167 void AliITSClusterFinderSSD::InitReconstruction(){
168 // initialization of the cluster finder
170 register Int_t i; //iterator
172 for (i=0;i<fNClusterP;i++) fClusterP->RemoveAt(i);
174 for (i=0;i<fNClusterN;i++) fClusterN->RemoveAt(i);
176 for (i=0;i<fNPackages;i++) fPackages->RemoveAt(i);
180 Float_t stereoP,stereoN;
181 GetSeg()->Angles(stereoP,stereoN);
182 CalcStepFactor(stereoP,stereoN);
183 AliDebug(1,Form("fSFF = %d fSFB = %d",fSFF,fSFB));
185 //______________________________________________________________________
186 void AliITSClusterFinderSSD::FindRawClusters(Int_t module){
187 // This function findes out all clusters belonging to one module
188 // 1. Zeroes all space after previous module reconstruction
189 // 2. Finds all neighbouring digits, create clusters
190 // 3. If necesery, resolves for each group of neighbouring digits
191 // how many clusters creates it.
192 // 4. Colculate the x and z coordinate
193 Int_t lay, lad, detect;
194 AliITSgeom *geom = fITS->GetITSgeom();
197 geom->GetModuleId(GetModule(),lay, lad, detect);
198 if ( lay == 6 ) ((AliITSsegmentationSSD*)GetSeg())->SetLayer(6);
199 if ( lay == 5 ) ((AliITSsegmentationSSD*)GetSeg())->SetLayer(5);
201 InitReconstruction(); //ad. 1
205 FindNeighbouringDigits(); //ad. 2
206 //SeparateOverlappedClusters(); //ad. 3
207 ClustersToPackages(); //ad. 4
210 //______________________________________________________________________
211 void AliITSClusterFinderSSD::FindNeighbouringDigits(){
212 //If there are any digits on this side, create 1st Cluster,
213 // add to it this digit, and increment number of clusters
216 if ((fNDigitsP>0 ) && (fNDigitsN > 0 )) {
217 Int_t currentstripNo;
218 Int_t *dbuffer = new Int_t [300]; //buffer for strip numbers
219 Int_t dnumber; //curent number of digits in buffer
220 TArrayI &lDigitsIndexP = *fDigitsIndexP;
221 TArrayI &lDigitsIndexN = *fDigitsIndexN;
222 TObjArray &lDigits = *(Digits());
223 TClonesArray &lClusterP = *fClusterP;
224 TClonesArray &lClusterN = *fClusterN;
227 dbuffer[0]=lDigitsIndexP[0];
228 //If next digit is a neigh. of previous, adds to last clust. this digit
229 for (i=1; i<fNDigitsP; i++) {
231 currentstripNo = ((AliITSdigitSSD*)lDigits[lDigitsIndexP[i]])->
233 //check if it is a neighbour of a previous one
234 if((((AliITSdigitSSD*)lDigits[lDigitsIndexP[i-1]])->
236 == (currentstripNo-1) ) dbuffer[dnumber++]=lDigitsIndexP[i];
238 //create a new one side cluster
239 new(lClusterP[fNClusterP++]) AliITSclusterSSD(dnumber,dbuffer,
242 dbuffer[0]=lDigitsIndexP[i];
245 } // end loop over fNDigitsP
246 new(lClusterP[fNClusterP++]) AliITSclusterSSD(dnumber,dbuffer,
249 //for comments, see above
251 dbuffer[0]=lDigitsIndexN[0];
252 //If next digit is a neigh. of previous, adds to last clust. this digit
253 for (i=1; i<fNDigitsN; i++) {
254 currentstripNo = ((AliITSdigitSSD*)(lDigits[lDigitsIndexN[i]]))->
256 if ( (((AliITSdigitSSD*)lDigits[lDigitsIndexN[i-1]])->
258 == (currentstripNo-1) ) dbuffer[dnumber++]=lDigitsIndexN[i];
260 new(lClusterN[fNClusterN++]) AliITSclusterSSD(dnumber,dbuffer,
263 dbuffer[0]=lDigitsIndexN[i];
266 } // end loop over fNDigitsN
267 new(lClusterN[fNClusterN++]) AliITSclusterSSD(dnumber,dbuffer,
271 } // end condition on NDigits
273 AliDebug(1,Form("\n Found clusters: fNClusterP = %d fNClusterN =%d",fNClusterP,fNClusterN));
275 //______________________________________________________________________
276 void AliITSClusterFinderSSD::SeparateOverlappedClusters(){
277 // overlapped clusters separation
278 register Int_t i; //iterator
279 Double_t factor=0.75; // How many percent must be lower signal
280 // on the middle one digit
281 // from its neighbours
282 Int_t signal0; //signal on the strip before the current one
283 Int_t signal1; //signal on the current one signal
284 Int_t signal2; //signal on the strip after the current one
285 TArrayI *splitlist; // List of splits
286 Int_t numerofsplits=0; // number of splits
287 Int_t initPsize = fNClusterP; //initial size of the arrays
288 Int_t initNsize = fNClusterN; //we have to keep it because it will grow
289 // in this function and it doasn't make
290 // sense to pass through it again
291 splitlist = new TArrayI(300);
293 for (i=0;i<initPsize;i++){
294 if (( ((AliITSclusterSSD*)(*fClusterP)[i])->
295 GetNumOfDigits())==1) continue;
296 if (( ((AliITSclusterSSD*)(*fClusterP)[i])->
297 GetNumOfDigits())==2) continue;
298 Int_t nj=(((AliITSclusterSSD*)(*fClusterP)[i])->GetNumOfDigits()-1);
299 for (Int_t j=1; j<nj; j++){
300 signal1=((AliITSclusterSSD*)(*fClusterP)[i])->GetDigitSignal(j);
301 signal0=((AliITSclusterSSD*)(*fClusterP)[i])->GetDigitSignal(j-1);
302 signal2=((AliITSclusterSSD*)(*fClusterP)[i])->GetDigitSignal(j+1);
303 //if signal is less then factor*signal of its neighbours
304 if ( (signal1<(factor*signal0)) && (signal1<(factor*signal2)) ){
305 (*splitlist)[numerofsplits++]=j;
307 } // end loop over number of digits
308 //split this cluster if necessary
309 if(numerofsplits>0) SplitCluster(splitlist,numerofsplits,i,fgkSIDEP);
311 //in signed places (splitlist)
312 } // end loop over clusters on Pside
314 for (i=0;i<initNsize;i++) {
315 if (( ((AliITSclusterSSD*)(*fClusterN)[i])->
316 GetNumOfDigits())==1) continue;
317 if (( ((AliITSclusterSSD*)(*fClusterN)[i])->
318 GetNumOfDigits())==2) continue;
319 Int_t nj=(((AliITSclusterSSD*)(*fClusterN)[i])->GetNumOfDigits()-1);
320 for (Int_t j=1; j<nj; j++){
321 signal1=((AliITSclusterSSD*)(*fClusterN)[i])->GetDigitSignal(j);
322 signal0=((AliITSclusterSSD*)(*fClusterN)[i])->GetDigitSignal(j-1);
323 signal2=((AliITSclusterSSD*)(*fClusterN)[i])->GetDigitSignal(j+1);
324 //if signal is less then factor*signal of its neighbours
325 if ( (signal1<(factor*signal0)) && (signal1<(factor*signal2)) )
326 (*splitlist)[numerofsplits++]=j;
327 } // end loop over number of digits
328 //split this cluster into more clusters
329 if(numerofsplits>0) SplitCluster(splitlist,numerofsplits,i,fgkSIDEN);
331 //in signed places (splitlist)
332 } // end loop over clusters on Nside
336 //______________________________________________________________________
337 void AliITSClusterFinderSSD::SplitCluster(TArrayI *list, Int_t nsplits,
338 Int_t index, Bool_t side){
339 //This function splits one side cluster into more clusters
340 //number of splits is defined by "nsplits"
341 //Place of splits are defined in the TArray "list"
342 // For further optimisation: Replace this function by two
343 // specialised ones (each for one side)
345 //For comlete comments see AliITSclusterSSD::SplitCluster
346 register Int_t i; //iterator
347 AliITSclusterSSD* curentcluster;
348 Int_t *tmpdigits = new Int_t[100];
351 // side true means P side
353 curentcluster =((AliITSclusterSSD*)((*fClusterP)[index])) ;
354 for (i = nsplits; i>0 ;i--) {
355 nn=curentcluster->SplitCluster((*list)[(i-1)],tmpdigits);
356 new ((*fClusterP)[fNClusterP]) AliITSclusterSSD(nn,tmpdigits,
358 ( (AliITSclusterSSD*)((*fClusterP)[fNClusterP]) )->
359 SetLeftNeighbour(kTRUE);
360 //if left cluster had neighbour on the right before split
361 //new should have it too
362 if ( curentcluster->GetRightNeighbour() )
363 ( (AliITSclusterSSD*)((*fClusterP)[fNClusterP]) )->
364 SetRightNeighbour(kTRUE);
365 else curentcluster->SetRightNeighbour(kTRUE);
367 } // end loop over nplits
369 curentcluster =((AliITSclusterSSD*)((*fClusterN)[index]));
370 for (i = nsplits; i>0 ;i--) {
371 nn=curentcluster->SplitCluster((*list)[(i-1)],tmpdigits);
372 new ((*fClusterN)[fNClusterN]) AliITSclusterSSD(nn,tmpdigits,
374 ((AliITSclusterSSD*)((*fClusterN)[fNClusterN]))->
375 SetRightNeighbour(kTRUE);
376 if (curentcluster->GetRightNeighbour())
377 ( (AliITSclusterSSD*)( (*fClusterN)[fNClusterN]) )->
378 SetRightNeighbour(kTRUE);
379 else curentcluster->SetRightNeighbour(kTRUE);
381 } // end loop over nplits
385 //______________________________________________________________________
386 Int_t AliITSClusterFinderSSD::SortDigitsP(Int_t start, Int_t end){
387 // sort digits on the P side
391 if (start != (end - 1) ){
392 left=this->SortDigitsP(start,(start+end)/2);
393 right=this->SortDigitsP((start+end)/2,end);
394 return (left || right);
396 left = ((AliITSdigitSSD*)((*(Digits()))[(*fDigitsIndexP)[start]]))->
398 right= ((AliITSdigitSSD*)((*(Digits()))[(*fDigitsIndexP)[end]]))->
401 Int_t tmp = (*fDigitsIndexP)[start];
402 (*fDigitsIndexP)[start]=(*fDigitsIndexP)[end];
403 (*fDigitsIndexP)[end]=tmp;
408 //______________________________________________________________________
409 Int_t AliITSClusterFinderSSD::SortDigitsN(Int_t start, Int_t end){
410 // sort digits on the N side
414 if (start != (end - 1)){
415 left=this->SortDigitsN(start,(start+end)/2);
416 right=this->SortDigitsN((start+end)/2,end);
417 return (left || right);
419 left =((AliITSdigitSSD*)((*(Digits()))[(*fDigitsIndexN)[start]]))->
421 right=((AliITSdigitSSD*)((*(Digits()))[(*fDigitsIndexN)[end]]))->
424 Int_t tmp = (*fDigitsIndexN)[start];
425 (*fDigitsIndexN)[start]=(*fDigitsIndexN)[end];
426 (*fDigitsIndexN)[end]=tmp;
431 //______________________________________________________________________
432 void AliITSClusterFinderSSD::FillDigitsIndex(){
433 //Fill the indexes of the clusters belonging to a given ITS module
439 noentries = NDigits();
441 Int_t* psidx = new Int_t [noentries*sizeof(Int_t)];
442 Int_t* nsidx = new Int_t [noentries*sizeof(Int_t)];
443 if (fDigitsIndexP==NULL) fDigitsIndexP = new TArrayI(noentries);
444 if (fDigitsIndexN==NULL) fDigitsIndexN = new TArrayI(noentries);
448 for ( i = 0 ; i< noentries; i++ ) {
449 dig = (AliITSdigitSSD*)GetDigit(i);
452 tmp=dig->GetStripNumber();
453 // I find this totally unnecessary - it's just a
454 // CPU consuming double check
457 AliDebug(1,"Such a digit exists");
463 fDigitsIndexP->AddAt(i,fNDigitsP++);
468 tmp=dig->GetStripNumber();
472 AliDebug(1,"Such a digit exists");
478 fDigitsIndexN->AddAt(i,fNDigitsN++);
487 AliDebug(1,Form("Digits: P = %d N = %d",fNDigitsP,fNDigitsN));
489 //______________________________________________________________________
490 void AliITSClusterFinderSSD::SortDigits(){
494 if(fNDigitsP>1) for (i=0;i<fNDigitsP-1;i++)
495 if (SortDigitsP(0,(fNDigitsP-1-i))==0) break;
496 if(fNDigitsN>1) for (i=0;i<fNDigitsN-1;i++)
497 if(SortDigitsN(0,(fNDigitsN-1-i))==0) break;
499 //______________________________________________________________________
500 void AliITSClusterFinderSSD::FillClIndexArrays(Int_t* arrayP,Int_t *arrayN)
502 // fill cluster index array
505 for (i=0; i<fNClusterP;i++) arrayP[i]=i;
506 for (i=0; i<fNClusterN;i++) arrayN[i]=i;
508 //______________________________________________________________________
509 void AliITSClusterFinderSSD::SortClusters(Int_t* arrayP, Int_t *arrayN){
513 if(fNClusterP>1) for (i=0;i<fNClusterP-1;i++)
514 if (SortClustersP(0,(fNClusterP-1),arrayP)==0) break;
515 if(fNClusterN>1) for (i=0;i<fNClusterN-1;i++)
516 if (SortClustersN(0,(fNClusterN-1),arrayN)==0) break;
518 //______________________________________________________________________
519 Int_t AliITSClusterFinderSSD::SortClustersP(Int_t start, Int_t end,
521 //Sort P side clusters
525 if (start != (end - 1) ) {
526 left=this->SortClustersP(start,(start+end)/2,array);
527 right=this->SortClustersP((start+end)/2,end,array);
528 return (left || right);
530 left =((AliITSclusterSSD*)((*fClusterP)[array[start]]))->
532 right=((AliITSclusterSSD*)((*fClusterP)[array[ end ]]))->
535 Int_t tmp = array[start];
536 array[start]=array[end];
542 //______________________________________________________________________
543 Int_t AliITSClusterFinderSSD::SortClustersN(Int_t start, Int_t end,
545 //Sort N side clusters
549 if (start != (end - 1) ) {
550 left=this->SortClustersN(start,(start+end)/2,array);
551 right=this->SortClustersN((start+end)/2,end,array);
552 return (left || right);
554 left =((AliITSclusterSSD*)((*fClusterN)[array[start]]))->
556 right=((AliITSclusterSSD*)((*fClusterN)[array[ end ]]))->
559 Int_t tmp = array[start];
560 array[start]=array[end];
566 //______________________________________________________________________
567 void AliITSClusterFinderSSD::ClustersToPackages(){
570 Int_t *oneSclP = new Int_t[fNClusterP];//I want to have sorted 1 S clusters
571 Int_t *oneSclN = new Int_t[fNClusterN];//I can not sort it in TClonesArray
572 //so, I create table of indexes and
574 //I do not use TArrayI on purpose
575 //MB: well, that's not true that one
576 //cannot sort objs in TClonesArray
577 AliITSclusterSSD *currentP;
578 AliITSclusterSSD *currentN;
581 //Fills in One Side Clusters Index Array
582 FillClIndexArrays(oneSclP,oneSclN);
583 //Sorts filled Arrays
584 //SortClusters(oneSclP,oneSclN);
587 new ((*fPackages)[0]) AliITSpackageSSD(fClusterP,fClusterN);
589 //This part was includede by Boris Batiounia in March 2001.
590 // Take all recpoint pairs (x coordinates) in both P and N sides
591 // to calculate z coordinates of the recpoints
593 for (j1=0;j1<fNClusterP;j1++) {
594 currentP = GetPSideCluster(oneSclP[j1]);
595 Double_t xP = currentP->GetPosition();
596 Double_t signalP = currentP->GetTotalSignal();
597 for (j2=0;j2<fNClusterN;j2++) {
598 currentN = GetNSideCluster(oneSclN[j2]);
599 Double_t xN = currentN->GetPosition();
600 Double_t signalN = currentN->GetTotalSignal();
601 CreateNewRecPoint(xP,1,xN,1,signalP,signalN,currentP,currentN,
609 //______________________________________________________________________
610 Bool_t AliITSClusterFinderSSD::CreateNewRecPoint(Double_t P,Double_t dP,
611 Double_t N, Double_t dN,
612 Double_t SigP,Double_t SigN,
613 AliITSclusterSSD *clusterP,
614 AliITSclusterSSD *clusterN,
616 // create the recpoints
617 const Double_t kADCtoKeV = 2.16;
618 // 50 ADC units -> 30000 e-h pairs; 1e-h pair -> 3.6e-3 KeV;
619 // 1 ADC unit -> (30000/50)*3.6e-3 = 2.16 KeV
620 const Double_t kconv = 1.0e-4;
621 const Double_t kRMSx = 20.0*kconv;
622 const Double_t kRMSz = 800.0*kconv;
627 if (GetCrossing(P,N)) {
628 //GetCrossingError(dP,dN);
629 dP = dN = prob = 0.0; // to remove unused variable warning.
630 AliITSRawClusterSSD cnew;
631 Int_t nstripsP=clusterP->GetNumOfDigits();
632 Int_t nstripsN=clusterN->GetNumOfDigits();
637 dedx = SigP*kADCtoKeV;
640 dedx = SigN*kADCtoKeV;
641 } // end if SigP>SigN
642 tr = (Int_t*) clusterP->GetTracks(n);
643 ntracks = clusterP->GetNTracks();
644 cnew.SetSignalP(SigP);
645 cnew.SetSignalN(SigN);
646 cnew.SetMultiplicity(nstripsP);
647 cnew.SetMultN(nstripsN);
648 cnew.SetQErr(TMath::Abs(SigP-SigN));
649 cnew.SetNTrack(ntracks);
650 fITS->AddCluster(2,&cnew);
656 rnew.SetSigmaX2( kRMSx* kRMSx);
657 rnew.SetSigmaZ2( kRMSz* kRMSz);
658 rnew.fTracks[0]=tr[0];
659 rnew.fTracks[1]=tr[1];
660 rnew.fTracks[2]=tr[2];
661 fITS->AddRecPoint(rnew);
666 //______________________________________________________________________
667 void AliITSClusterFinderSSD::CalcStepFactor(Double_t Psteo, Double_t Nsteo){
668 // calculate the step factor for matching clusters
669 // 95 is the pitch, 4000 - dimension along z ?
670 Double_t dz=GetSeg()->Dz();
672 fSFF = ( (Int_t) (Psteo*dz/fPitch ) );// +1;
673 fSFB = ( (Int_t) (Nsteo*dz/fPitch ) );// +1;
675 //______________________________________________________________________
676 AliITSclusterSSD* AliITSClusterFinderSSD::GetPSideCluster(Int_t idx){
677 // get P side clusters
679 if((idx<0)||(idx>=fNClusterP)){
680 Info("GetPSideCluster","0<index=%d<=%d out of range",idx,fNClusterP);
683 return (AliITSclusterSSD*)((*fClusterP)[idx]);
686 //______________________________________________________________________
687 AliITSclusterSSD* AliITSClusterFinderSSD::GetNSideCluster(Int_t idx){
688 // get N side clusters
690 if((idx<0)||(idx>=fNClusterN)){
691 Info("GetNSideCluster","0<index=%d >= %d out of range",idx,fNClusterN);
694 return (AliITSclusterSSD*)((*fClusterN)[idx]);
697 //______________________________________________________________________
698 Bool_t AliITSClusterFinderSSD::GetCrossing (Double_t &P, Double_t &N){
700 // This function was rivised and changed by Boris Batiounia in March 2001
701 Double_t dx = GetSeg()->Dx(); // detector size in x direction, microns
702 Double_t dz = GetSeg()->Dz(); // detector size in z direction, microns
703 Double_t xL; // x local coordinate
704 Double_t zL; // z local coordinate
705 Double_t x; // x = xL + dx/2
706 Double_t z; // z = zL + dz/2
707 Double_t xP; // x coordinate in the P side from the first P strip
708 Double_t xN; // x coordinate in the N side from the first N strip
709 Float_t stereoP,stereoN;
711 GetSeg()->Angles(stereoP,stereoN);
712 fTanP=TMath::Tan(stereoP);
713 fTanN=TMath::Tan(stereoN);
714 Double_t kP = fTanP; // Tangent of 0.0075 mrad
715 Double_t kN = fTanN; // Tangent of 0.0275 mrad
719 xP = N; // change the mistake for the P/N
720 xN = P; // coordinates correspondence in this function
722 x = xP + kP*(dz*kN-xP+xN)/(kP+kN);
723 z = (dz*kN-xP+xN)/(kP+kN);
729 if(TMath::Abs(xL) > dx/2 || TMath::Abs(zL) > dz/2) return kFALSE;
731 // Check that xL and zL are inside the detector for the
732 // correspondent xP and xN coordinates
736 //______________________________________________________________________
737 void AliITSClusterFinderSSD::GetCrossingError(Double_t& dP, Double_t& dN){
738 // get crossing error
741 dz = TMath::Abs(( dP + dN )*fPitch/(fTanP + fTanN) );
742 dx = fPitch*(TMath::Abs(dP*(1 - fTanP/(fTanP + fTanN))) +
743 TMath::Abs(dN *fTanP/(fTanP + fTanN) ));