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 **************************************************************************/
18 Revision 1.4.10.1 2002/08/28 15:06:52 alibrary
21 Revision 1.5 2002/08/25 15:54:29 kowal2
22 Protection against overflows in TMath::Nint.
24 Revision 1.4 2001/01/10 09:35:27 kowal2
25 Changes to obey the coding rules.
27 Revision 1.3 2000/11/02 10:22:50 kowal2
31 ///////////////////////////////////////////////////////////////////////////////
33 // Time Projection Chamber track hits object //
35 // Origin: Marian Ivanov , GSI Darmstadt
37 // Class for storing simulated AliTPCHits for given track //
38 // -average compression comparing to classical ClonesArray is //
39 // around 5-7 (depending on the required hit precision) //
43 <img src="gif/AliTPCTrackHits.gif">
48 ///////////////////////////////////////////////////////////////////////////////
51 #include "TClonesArray.h"
52 #include "AliTPCTrackHits.h"
59 ClassImp(AliTPCTrackHits)
60 LClassImp(AliTrackHitsInfo)
61 LClassImp(AliTrackHitsParam)
64 Int_t AliTrackHitsInfo::fgCounter1 =0;
65 Int_t AliTrackHitsInfo::fgCounter2 =0;
66 Int_t AliTrackHitsParam::fgCounter1 =0;
67 Int_t AliTrackHitsParam::fgCounter2 =0;
68 Int_t AliHitInfo::fgCounter1 =0;
69 Int_t AliHitInfo::fgCounter2 =0;
70 Int_t AliTPCTrackHits::fgCounter1 =0;
71 Int_t AliTPCTrackHits::fgCounter2 =0;
72 const Double_t AliTPCTrackHits::fgkPrecision=1e-6; //precision
73 const Double_t AliTPCTrackHits::fgkPrecision2=1e-20; //precision
76 /************************************************************/
77 // Interface classes //
78 #include "AliTPCTrackHitsInterfaces.h"
83 struct AliTPCCurrentHit {
85 UInt_t fInfoIndex;// - current info pointer
86 UInt_t fParamIndex;// - current param pointer
87 UInt_t fStackIndex; // - current hit stack index
88 Double_t fR; //current Radius
89 Bool_t fStatus; //current status
93 struct AliTPCTempHitInfo {
94 enum { fkStackSize = 10000};
96 void NewParam(Double_t r, Double_t z, Double_t fi, Int_t q);
97 void SetHit(Double_t r, Double_t z, Double_t fi, Int_t q);
98 Double_t * GetPosition(Int_t index){return &fPositionStack[index*3];}
99 void UpdateParam(Double_t maxdelta); //recal
100 void Fit2(Double_t fSumY, Double_t fSumYX, Double_t fSumYX2,
101 Double_t fSumX, Double_t fSumX2, Double_t fSumX3,
102 Double_t fSumX4, Int_t n,
103 Double_t &a, Double_t &b, Double_t &c);
104 void Fit(AliTrackHitsParam * param);
110 Double_t fSumDFiDr; //
111 Double_t fSumDFiDr2;//
113 Double_t fSumDZDr; //
114 Double_t fSumDZDr2; //
115 Double_t fOldR; //previos r
116 Double_t fPositionStack[3*fkStackSize]; //position stack
117 UInt_t fQStack[fkStackSize]; //Q stack
118 UInt_t fStackIndex; //current stack index
119 UInt_t fInfoIndex; //current track info index
120 UInt_t fParamIndex; //current track parameters index
121 AliTrackHitsInfo * fInfo; //current track info
122 AliTrackHitsParam * fParam; //current track param
126 AliTPCTempHitInfo::AliTPCTempHitInfo()
129 //set to default value
130 fSumDr=fSumDr2=fSumDr3=fSumDr4=
131 fSumDFi=fSumDFiDr=fSumDFiDr2=
132 fSumDZ=fSumDZDr=fSumDZDr2=0;
139 void AliTPCTempHitInfo::NewParam(Double_t r, Double_t z, Double_t fi, Int_t q)
142 //reset stack and sum parameters
143 //store line initial point
144 fSumDr=fSumDr2=fSumDr3=fSumDr4=
145 fSumDFi=fSumDFiDr=fSumDFiDr2=
146 fSumDZ=fSumDZDr=fSumDZDr2=0;
159 void AliTPCTempHitInfo::SetHit(Double_t r, Double_t z, Double_t fi, Int_t q)
162 //add hit to the stack
163 //recalculate new estimete of line parameters
164 Double_t *f = GetPosition(fStackIndex);
168 fQStack[fStackIndex]=q;
169 if (fStackIndex==0) return;
170 Double_t dr = (r-fParam->fR);
171 if (TMath::Abs(dr)<AliTPCTrackHits::fgkPrecision) dr =AliTPCTrackHits::fgkPrecision;
172 Double_t dfi = fi-fParam->fFi;
173 Double_t dz = z -fParam->fZ;
175 Double_t dr3 =dr2*dr;
176 Double_t dr4 =dr3*dr;
188 //update fit parameters
190 Double_t det = fSumDr2*fSumDr4-fSumDr3*fSumDr3;
191 if (TMath::Abs(det)<AliTPCTrackHits::fgkPrecision2) return;
192 if ( ( fStackIndex>1 ) ){
193 fParam->fAn = (fSumDr4*fSumDFiDr-fSumDr3*fSumDFiDr2)/det;
194 fParam->fAd = (fSumDr2*fSumDFiDr2-fSumDr3*fSumDFiDr)/det;
197 fParam->fAn = fSumDFiDr/fSumDr2;
198 if ( ( fStackIndex>1 ) ){
199 fParam->fTheta = (fSumDr4*fSumDZDr-fSumDr3*fSumDZDr2)/det;
200 fParam->fThetaD= (fSumDr2*fSumDZDr2-fSumDr3*fSumDZDr)/det;
203 fParam->fTheta = fSumDZDr/fSumDr2;
207 void AliTPCTempHitInfo::UpdateParam(Double_t maxdelta)
209 //recalc parameters not fixing origin point
213 Fit2(fSumDFi, fSumDFiDr, fSumDFiDr2, fSumDr,fSumDr2,fSumDr3,fSumDr4,
215 if (TMath::Abs(a)<maxdelta){
216 fParam->fFi +=a/fParam->fR;
220 Fit2(fSumDZ, fSumDZDr, fSumDZDr2, fSumDr,fSumDr2,fSumDr3,fSumDr4,
221 fStackIndex, a,b,c) ;
222 if (TMath::Abs(a)<maxdelta){
230 void AliTPCTempHitInfo::Fit2(Double_t fSumY, Double_t fSumYX, Double_t fSumYX2,
231 Double_t fSumX, Double_t fSumX2, Double_t fSumX3,
232 Double_t fSumX4, Int_t n,
233 Double_t &a, Double_t &b, Double_t &c)
235 //fit of second order
237 n* (fSumX2*fSumX4-fSumX3*fSumX3) -
238 fSumX* (fSumX*fSumX4-fSumX3*fSumX2)+
239 fSumX2* (fSumX*fSumX3-fSumX2*fSumX2);
241 if (TMath::Abs(det)> AliTPCTrackHits::fgkPrecision) {
243 (fSumY * (fSumX2*fSumX4-fSumX3*fSumX3)-
244 fSumX *(fSumYX*fSumX4-fSumYX2*fSumX3)+
245 fSumX2*(fSumYX*fSumX3-fSumYX2*fSumX2))/det;
247 (n*(fSumYX*fSumX4-fSumX3*fSumYX2)-
248 fSumY*(fSumX*fSumX4-fSumX3*fSumX2)+
249 fSumX2*(fSumX*fSumYX2-fSumYX*fSumX2))/det;
251 (n*(fSumX2*fSumYX2-fSumYX*fSumX3)-
252 fSumX*(fSumX*fSumYX2-fSumYX*fSumX2)+
253 fSumY*(fSumX*fSumX3-fSumX2*fSumX2))/det;
257 void AliTPCTempHitInfo::Fit(AliTrackHitsParam * param)
259 // fit fixing first and the last point
260 //result stored in new param
261 Double_t dx2 = (GetPosition(fStackIndex))[0]-fParam->fR;
262 Double_t det = fSumDr4+dx2*fSumDr2-2*dx2*fSumDr3;
263 if ( (TMath::Abs(det)> AliTPCTrackHits::fgkPrecision) &&
264 ((TMath::Abs(dx2)> AliTPCTrackHits::fgkPrecision))){
265 Double_t dfi2 = (GetPosition(fStackIndex))[1]-fParam->fFi;
266 param->fAd = (fSumDFiDr2+dfi2*fSumDr-dx2*fSumDFiDr-dfi2*fSumDr3/dx2)/det;
267 param->fAn = (dfi2-param->fAd*dx2*dx2)/dx2;
269 Double_t dz2 = (GetPosition(fStackIndex))[1]-fParam->fZ;
270 param->fTheta = (fSumDZDr2+dz2*fSumDr-dx2*fSumDZDr-dz2*fSumDr3/dx2)/det;
271 param->fTheta = (dz2-param->fAd*dx2*dx2)/dx2;
279 AliTPCTrackHits::AliTPCTrackHits()
282 //default constructor
284 const Float_t kHitPrecision=0.002; //default precision for hit position in cm
285 const Float_t kStep =0.003; //30 mum step
286 const UShort_t kMaxDistance =100; //maximum distance 100
288 fPrecision=kHitPrecision; //precision in cm
289 fStep = kStep; //step size
290 fMaxDistance = kMaxDistance; //maximum distance
292 fTrackHitsInfo = new AliObjectArray("AliTrackHitsInfo");
293 fTrackHitsParam = new AliObjectArray("AliTrackHitsParam");
294 fHitsPosAndQ = new TArrayOfArrayVStack("AliHitInfo");
295 fCurrentHit = new AliTPCCurrentHit;
301 AliTPCTrackHits::~AliTPCTrackHits()
306 if (fTrackHitsInfo) delete fTrackHitsInfo;
307 if (fTrackHitsParam) delete fTrackHitsParam;
308 if (fHitsPosAndQ) delete fHitsPosAndQ;
309 if (fCurrentHit) delete fCurrentHit;
310 if (fTempInfo) delete fTempInfo;
314 void AliTPCTrackHits::Clear()
318 fTrackHitsInfo->Clear();
319 fTrackHitsParam->Clear();
320 //fTrackHitsInfo->Resize(0);
321 //fTrackHitsParam->Resize(0);
322 fHitsPosAndQ->Clear();
331 void AliTPCTrackHits::AddHitKartez(Int_t volumeID, Int_t trackID, Double_t x,
332 Double_t y, Double_t z,Int_t q)
334 Double_t r = TMath::Sqrt(x*x+y*y);
335 Double_t fi = TMath::ACos(x/r);
337 AddHit(volumeID,trackID,r,z,fi,q);
340 void AliTPCTrackHits::AddHit(Int_t volumeID, Int_t trackID,
341 Double_t r, Double_t z, Double_t fi, Int_t q)
345 if (!fTempInfo) { //initialsation of track
346 fTempInfo = new AliTPCTempHitInfo;
348 if (fTrackHitsInfo->GetCapacity()<10) fTrackHitsInfo->Reserve(10);
349 fTrackHitsInfo->Resize(1);
350 fTempInfo->fInfoIndex =0;
351 if (fTrackHitsParam->GetCapacity()<100) fTrackHitsParam->Reserve(100);
352 fTrackHitsParam->Resize(1);
355 (AliTrackHitsInfo*) (fTrackHitsInfo->At(0));
356 fTempInfo->fInfo->fVolumeID = volumeID;
357 fTempInfo->fInfo->fTrackID = trackID;
358 fTempInfo->fInfo->fHitParamIndex =0;
359 fTempInfo->fInfoIndex = 0;
362 (AliTrackHitsParam*) (fTrackHitsParam->At(0));
363 fTempInfo->fParamIndex = 0;
364 fTempInfo->NewParam(r,z,fi,q);
368 Int_t size = fHitsPosAndQ->GetSize();
369 if (size>(Int_t)fTempInfo->fParamIndex) {
370 fTempInfo->fParamIndex++;
371 if (fTempInfo->fParamIndex+1>fTrackHitsParam->GetSize())
372 fTrackHitsParam->Resize(fTempInfo->fParamIndex+1);
374 (AliTrackHitsParam*) (fTrackHitsParam->At(fTempInfo->fParamIndex));
375 fTempInfo->NewParam(r,z,fi,q);
380 // if new volume or new trackID
381 if ( (volumeID!=fTempInfo->fInfo->fVolumeID) ||
382 (trackID!=fTempInfo->fInfo->fTrackID)){
385 FlushHitStack(kTRUE);
387 fTempInfo->fInfoIndex++;
388 if (fTempInfo->fInfoIndex+1>fTrackHitsInfo->GetSize())
389 fTrackHitsInfo->Resize(fTempInfo->fInfoIndex+1);
391 (AliTrackHitsInfo*) (fTrackHitsInfo->At(fTempInfo->fInfoIndex));
392 fTempInfo->fInfo->fVolumeID = volumeID;
393 fTempInfo->fInfo->fTrackID = trackID;
394 fTempInfo->fInfo->fHitParamIndex =fTempInfo->fParamIndex+1;
395 // FlushHitStack(kTRUE);
397 fTempInfo->fParamIndex++;
398 if (fTempInfo->fParamIndex+1>fTrackHitsParam->GetSize())
399 fTrackHitsParam->Resize(fTempInfo->fParamIndex+1);
401 (AliTrackHitsParam*) (fTrackHitsParam->At(fTempInfo->fParamIndex));
402 fTempInfo->NewParam(r,z,fi,q);
406 //calculate current fit precission to next point
407 AliTrackHitsParam ¶m = *(fTempInfo->fParam);
411 Double_t dr,dz,dfi,ddz,ddfi;
413 dr=dz=dfi=ddz=ddfi=0;
414 drhit = r-fTempInfo->fOldR;
416 //Double_t dfi2 = param.fAn+2*param.fAd*(r-param.fR);
417 Double_t dfi2 = param.fAn;
418 dfi2*=dfi2*fTempInfo->fOldR*fTempInfo->fOldR;
419 //Double_t ddz2 = param.fTheta+2*param.fThetaD*(r-param.fR);
420 Double_t ddz2 = param.fTheta;
422 ratio = TMath::Sqrt(1.+ dfi2+ ddz2);
427 dl = (TMath::Abs(drhit*ratio/fStep)<32000) ? fStep * Short_t(TMath::Nint(drhit*ratio/fStep)):0;
428 ddl = dl - drhit*ratio;
429 fTempInfo->fOldR += dl/ratio;
431 if (fTempInfo->fStackIndex>2){
435 ddz = dr*param.fTheta+dr*dr*param.fThetaD-dz;
436 ddfi= dr*param.fAn+dr*dr*param.fAd-dfi;
437 dd = TMath::Sqrt(ddz*ddz+r*r*ddfi*ddfi+ddl*ddl);
441 if ( ( (dd*1.25>fPrecision) ) ||
442 (fTempInfo->fStackIndex+4>fTempInfo->fkStackSize) ||
443 (TMath::Abs(dl/fStep)>fMaxDistance) )
446 fTempInfo->fStackIndex++;
447 fTempInfo->SetHit(r,z,fi,q);
450 //if parameter changed
451 if (FlushHitStack(kFALSE)){ //if full buffer flushed
452 fTempInfo->fParamIndex++;
453 if (fTempInfo->fParamIndex+1>fTrackHitsParam->GetSize())
454 fTrackHitsParam->Resize(fTempInfo->fParamIndex+1);
456 (AliTrackHitsParam*) (fTrackHitsParam->At(fTempInfo->fParamIndex));
457 fTempInfo->NewParam(r,z,fi,q);
460 fTempInfo->fStackIndex++;
461 fTempInfo->SetHit(r,z,fi,q);
465 Bool_t AliTPCTrackHits::FlushHitStack(Bool_t force)
468 //write fHitsPosAndQ information from the stack to te arrays
469 if (!fTempInfo) return kFALSE;
470 Int_t size = fHitsPosAndQ->GetSize();
472 if ( (size>0)&&(size!=(Int_t)fTempInfo->fParamIndex)) return kFALSE;
474 if (fHitsPosAndQ->Push(fTempInfo->fStackIndex+1)!=fTempInfo->fParamIndex){
475 cout<<"internal error - contact MI\n";
480 AliTrackHitsParam & param = *(fTempInfo->fParam);
481 //recalculate track parameter not fixing first point
482 fTempInfo->UpdateParam(fStep/4.);
483 //fTempInfo->Fit(fTempInfo->fParam); //- fixing the first and the last point
485 Double_t oldr = param.fR;
486 //cout<<"C3"<<fTempInfo->fStackIndex<<"\n"<<flush;
489 for (i=0; i <= fTempInfo->fStackIndex; i++){
490 Double_t * position = fTempInfo->GetPosition(i);
491 Double_t dr = position[0]-oldr;
494 //Double_t dfi2 = param.fAn+2*param.fAd*(position[0]-param.fR);
495 Double_t dfi2 = param.fAn;
496 dfi2*=dfi2*oldr*oldr;
497 //Double_t ddz2 = param.fTheta+2*param.fThetaD*(position[0]-param.fR);
498 Double_t ddz2 = param.fTheta;
500 ratio = TMath::Sqrt(1.+ dfi2+ ddz2);
503 Double_t dl = (TMath::Abs(dr*ratio/fStep)<32000) ? fStep*(Short_t)TMath::Nint(dr*ratio/fStep):0;
506 //calculate precission
507 AliTrackHitsParam ¶m = *(fTempInfo->fParam);
509 Double_t dr1= position[0]-param.fR;
510 Double_t dz = position[1]-param.fZ;
512 Double_t dfi = position[2]-param.fFi;
513 //extrapolated deltas
514 Double_t dr2 = oldr-param.fR;
515 Double_t ddr = dr2-dr1;
516 Double_t ddz = dr2*param.fTheta+dr2*dr2*param.fThetaD-dz;
517 Double_t ddfi= dr2*param.fAn+dr2*dr2*param.fAd-dfi;
518 dd = TMath::Sqrt(ddz*ddz+oldr*oldr*ddfi*ddfi+ddr*ddr);
520 if ( (dd>fPrecision) ){
526 Double_t ddz = dr2*param.fTheta+dr2*dr2*param.fThetaD-dz;
527 Double_t ddfi= dr2*param.fAn+dr2*dr2*param.fAd-dfi;
529 dd = TMath::Sqrt(ddz*ddz+oldr*oldr*ddfi*ddfi+ddr*ddr);
535 info = (AliHitInfo*)(fHitsPosAndQ->At(fTempInfo->fParamIndex,i));
536 info->fHitDistance = (TMath::Abs(dl/fStep)<32000) ?Short_t(TMath::Nint(dl/fStep)):0;
537 info->fCharge = Short_t(fTempInfo->fQStack[i]);
540 cout<<" "<<fTempInfo->fStackIndex<<" \t";
542 cout<<position[0]<<"\t";
543 cout<<position[1]<<"\t";
544 cout<<position[2]<<"\t";
545 cout<<param.fAn<<"\t";
546 cout<<param.fTheta<<"\t";
547 cout<<dr1<<"\t"<<ddr<<"\t"<<ddz<<"\t"<<ddfi<<"\t"<<dd<<"\n"<<flush;
551 if (i<=fTempInfo->fStackIndex){ //if previous iteration not succesfull
552 fHitsPosAndQ->Resize(fTempInfo->fParamIndex,i);
554 fTempInfo->fParamIndex++;
555 if (fTempInfo->fParamIndex+1>fTrackHitsParam->GetSize())
556 fTrackHitsParam->Resize(fTempInfo->fParamIndex+1);
558 (AliTrackHitsParam*) (fTrackHitsParam->At(fTempInfo->fParamIndex));
559 Double_t * p = fTempInfo->GetPosition(i);
560 UInt_t index2 = fTempInfo->fStackIndex;
561 fTempInfo->NewParam(p[0],p[1],p[2],fTempInfo->fQStack[i]);
562 if (i+1<=index2) FlushHitStack2(i+1,index2);
564 if (force) return FlushHitStack(kTRUE);
571 void AliTPCTrackHits::FlushHitStack2(Int_t index1, Int_t index2)
574 // second iteration flush stack
575 // call only for hits where first iteration were not succesfully interpolated
576 Double_t * positionstack = new Double_t[3*(index2-index1+1)];
577 UInt_t * qstack = new UInt_t[index2-index1+1];
578 memcpy(positionstack, &fTempInfo->fPositionStack[3*index1],
579 (3*(index2-index1+1))*sizeof(Double_t));
580 memcpy(qstack, &fTempInfo->fQStack[index1],(index2-index1+1)*sizeof(UInt_t));
581 Double_t *p = positionstack;
582 for (Int_t j=0; j<=index2-index1;j++){
583 fTempInfo->fStackIndex++;
584 fTempInfo->SetHit(p[3*j+0],p[3*j+1],p[3*j+2],qstack[j]);
586 delete []positionstack;
598 Bool_t AliTPCTrackHits::First()
601 //set Current hit for the first hit
603 AliTrackHitsInfo *info = (AliTrackHitsInfo *)fTrackHitsInfo->At(0);
604 AliTrackHitsParam *param = (AliTrackHitsParam *)fTrackHitsParam->At(0);
605 AliHitInfo * hinfo = (AliHitInfo *)fHitsPosAndQ->At(0,0);
607 if (!(info) || !(param) || !(hinfo) ) {
608 fCurrentHit->fStatus = kFALSE;
612 fCurrentHit->fInfoIndex = 0;
613 fCurrentHit->fParamIndex = 0;
614 fCurrentHit->fStackIndex = 0;
616 fCurrentHit->fHit.fSector = info->fVolumeID;
617 fCurrentHit->fHit.SetTrack(info->fTrackID);
618 fCurrentHit->fHit.SetX(param->fR*TMath::Cos(param->fFi));
619 fCurrentHit->fHit.SetY(param->fR*TMath::Sin(param->fFi));
620 fCurrentHit->fHit.SetZ(param->fZ);
621 fCurrentHit->fHit.fQ = hinfo->fCharge;
623 fCurrentHit->fR = param->fR;
625 return fCurrentHit->fStatus = kTRUE;
628 Bool_t AliTPCTrackHits::Next()
632 if (!(fCurrentHit->fStatus))
635 fCurrentHit->fStackIndex++;
636 AliHitInfo * hinfo = (AliHitInfo *)fHitsPosAndQ->At(fCurrentHit->fParamIndex,
637 fCurrentHit->fStackIndex);
638 AliTrackHitsInfo *info = (AliTrackHitsInfo *)fTrackHitsInfo->At(fCurrentHit->fInfoIndex);
639 AliTrackHitsParam *param = (AliTrackHitsParam *)fTrackHitsParam->At(fCurrentHit->fParamIndex);
642 hinfo = (AliHitInfo *)fHitsPosAndQ->At(fCurrentHit->fParamIndex+1, 0);
644 return fCurrentHit->fStatus = kFALSE;
646 fCurrentHit->fParamIndex++;
647 fCurrentHit->fStackIndex = 0;
648 param = (AliTrackHitsParam *)fTrackHitsParam->At(fCurrentHit->fParamIndex);
650 return fCurrentHit->fStatus = kFALSE;
651 fCurrentHit->fR = param->fR;
653 if ((fCurrentHit->fInfoIndex+1<fTrackHitsInfo->GetSize())
654 &&((info+1)->fHitParamIndex<=fCurrentHit->fParamIndex)){
655 fCurrentHit->fInfoIndex++;
656 info = (AliTrackHitsInfo *)fTrackHitsInfo->At(fCurrentHit->fInfoIndex);
658 return fCurrentHit->fStatus = kFALSE;
659 fCurrentHit->fHit.fSector = info->fVolumeID;
660 fCurrentHit->fHit.SetTrack(info->fTrackID);
666 // Double_t dfi2 = param->fAn+2*param->fAd*(fCurrentHit->fR-param->fR);
667 Double_t dfi2 = param->fAn;
668 dfi2*=dfi2*fCurrentHit->fR*fCurrentHit->fR;
669 // Double_t ddz2 = param->fTheta+2*param->fThetaD*(fCurrentHit->fR-param->fR);
670 Double_t ddz2 = param->fTheta;
672 ratio = TMath::Sqrt(1.+ dfi2+ ddz2);
675 fCurrentHit->fHit.fQ = hinfo->fCharge;
676 fCurrentHit->fR += fStep*hinfo->fHitDistance/ratio;
677 Double_t dR = fCurrentHit->fR - param->fR;
679 Double_t fi = param->fFi + (param->fAn*dR+param->fAd*dR*dR);
680 Double_t z = param->fZ + (param->fTheta*dR+param->fThetaD*dR*dR);
682 fCurrentHit->fHit.SetX(fCurrentHit->fR*TMath::Cos(fi));
683 fCurrentHit->fHit.SetY(fCurrentHit->fR*TMath::Sin(fi));
684 fCurrentHit->fHit.SetZ(z);
688 AliTPChit * AliTPCTrackHits::GetHit()
691 return (fCurrentHit->fStatus)? &fCurrentHit->fHit:0;
692 //return &fCurrentHit->fHit;
696 AliTrackHitsParam * AliTPCTrackHits::GetParam()
699 return (fCurrentHit->fStatus)? (AliTrackHitsParam *)fTrackHitsParam->At(fCurrentHit->fParamIndex) :0;
702 AliHitInfo * AliTPCTrackHits::GetHitInfo()
705 return (fCurrentHit->fStatus)?
706 (AliHitInfo *)fHitsPosAndQ->At(fCurrentHit->fParamIndex,fCurrentHit->fStackIndex) :0;