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[u/mrichter/AliRoot.git] / HLT / TPCLib / AliHLTTPCFitter.cxx
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a6c02c85 1// @(#) $Id$
4aa41877 2// Original: AliHLTFitter.cxx,v 1.14 2005/06/14 10:55:21 cvetan
a6c02c85 3
4// Author: Anders Vestbo <mailto:vestbo@fi.uib.no>
5//*-- Copyright &copy ALICE HLT Group
6
7/** \class AliHLTTPCFitter
8<pre>
9//_____________________________________________________________
10// AliHLTTPCFitter
11//
12// Fit class HLT for helix
13</pre>
14*/
15
16#include <math.h>
a6c02c85 17#include "AliHLTTPCLogging.h"
18#include "AliHLTTPCFitter.h"
19#include "AliHLTTPCVertex.h"
20#include "AliHLTTPCTrack.h"
21#include "AliHLTTPCSpacePointData.h"
22#include "AliHLTTPCMemHandler.h"
23#include "AliHLTTPCTransform.h"
a7c32962 24//#include "AliHLTTPC.h"
a6c02c85 25
26#if __GNUC__ >= 3
27using namespace std;
28#endif
29
30ClassImp(AliHLTTPCFitter)
31
32
33AliHLTTPCFitter::AliHLTTPCFitter()
34{
35 //constructor
36 fTrack=0;
37 fVertex=0;
38 memset(fClusters,0,36*6*sizeof(AliHLTTPCSpacePointData*));
39}
40
41AliHLTTPCFitter::AliHLTTPCFitter(AliHLTTPCVertex *vertex,Bool_t vertexconstraint)
42{
43 //constructor
44 fTrack=0;
45 fVertex = vertex;
46 fVertexConstraint=vertexconstraint;
47 memset(fClusters,0,36*6*sizeof(AliHLTTPCSpacePointData*));
48}
49
50AliHLTTPCFitter::~AliHLTTPCFitter()
51{
52 //destructor
53 for(Int_t i=0; i<36; i++)
54 {
55 for(Int_t j=0; j<6; j++)
56 {
57 if(fClusters[i][j])
58 delete [] fClusters[i][j];
59 }
60 }
61}
62
63void AliHLTTPCFitter::LoadClusters(Char_t *path,Int_t event,Bool_t sp)
64{
65 //load clusters
66 Char_t fname[256];
67 AliHLTTPCMemHandler *clusterfile[36][6];
68 for(Int_t s=0; s<=35; s++)
69 {
70 for(Int_t p=0; p<6; p++)
71 {
72 Int_t patch;
73 if(sp==kTRUE)
74 patch=-1;
75 else
76 patch=p;
77 if(fClusters[s][p])
78 delete fClusters[s][p];
79 fClusters[s][p] = 0;
80 clusterfile[s][p] = new AliHLTTPCMemHandler();
81 sprintf(fname,"%s/points_%d_%d_%d.raw",path,event,s,patch);
82 if(!clusterfile[s][p]->SetBinaryInput(fname))
83 {
84 delete clusterfile[s][p];
85 clusterfile[s][p] = 0;
86 continue;
87 }
88 fClusters[s][p] = (AliHLTTPCSpacePointData*)clusterfile[s][p]->Allocate();
89 clusterfile[s][p]->Binary2Memory(fNcl[s][p],fClusters[s][p]);
90 clusterfile[s][p]->CloseBinaryInput();
91 if(sp==kTRUE)
92 break;
93 }
94 }
95}
96
97void AliHLTTPCFitter::SortTrackClusters(AliHLTTPCTrack *track) const
98{
99 //Sort the internal cluster list in each track with respect to row numbering.
100 //This may be necessary when no conventional track follower has been
101 //applied, in which the cluster list has been maintained in a more
102 //arbitrary fashion.
103
104 Int_t nhits = track->GetNHits();
105 Int_t *ids = (Int_t*)track->GetHitNumbers();
106 Int_t *origids = new Int_t[nhits];
107 Int_t *mk = new Int_t[nhits];
108 Int_t k;
109
110 for(k=0; k<nhits; k++) {origids[k] = ids[k]; mk[k] = -1;}
111
112 Int_t slice,patch,id,padrow,maxrow,maxk;
113 UInt_t pos;
114 for(Int_t j=0; j<nhits; j++)
115 {
116 maxrow=-1;
117 maxk=200;
118 for(k=0; k<nhits; k++)
119 {
120 id=ids[k];
121 if(id < 0) continue;
122 slice = (id>>25) & 0x7f;
123 patch = (id>>22) & 0x7;
124 pos = id&0x3fffff;
125 AliHLTTPCSpacePointData *points = fClusters[slice][patch];
126 padrow = points[pos].fPadRow;
127 if(padrow > maxrow)
128 {
129 maxrow = padrow;
130 maxk=k;
131 }
132 }
133 mk[j]=maxk;
134 ids[maxk]=-1;
135 }
136
137 for(k=0; k<nhits; k++)
138 ids[k] = origids[mk[k]];
139 delete [] origids;
140 delete [] mk;
141}
142
143Int_t AliHLTTPCFitter::FitHelix(AliHLTTPCTrack *track)
144{
145 //fit helix parameters
146 fTrack = track;
147 if(FitCircle())
148 {
149 LOG(AliHLTTPCLog::kError,"AliHLTTPCFitter::FitHelix","TrackFit")<<AliHLTTPCLog::kDec<<
150 "Problems during circle fit"<<ENDLOG;
151 return 1;
152 }
153 if(FitLine())
154 {
155 LOG(AliHLTTPCLog::kError,"AliHLTTPCFitter::FitHelix","TrackFit")<<AliHLTTPCLog::kDec<<
156 "Problems during line fit"<<ENDLOG;
157 return 1;
158 }
159 return 0;
160}
161
162Int_t AliHLTTPCFitter::FitCircle()
163{
164 //-----------------------------------------------------------------
165 //Fits circle parameters using algorithm
166 //described by ChErnov and Oskov in Computer Physics
167 //Communications.
168 //
169 //Written in FORTRAN by Jawluen Tang, Physics department , UT-Austin
170 //Moved to C by Pablo Yepes
171 //Moved to AliROOT by ASV.
172 //------------------------------------------------------------------
173
174 Double_t wsum = 0.0 ;
175 Double_t xav = 0.0 ;
176 Double_t yav = 0.0 ;
177
178 //
179 // Loop over hits calculating average
180 Double_t * fXYWeight = new Double_t[(fTrack->GetNHits())];
181 UInt_t *hitnum = fTrack->GetHitNumbers();
182 for(Int_t i=0; i<fTrack->GetNHits(); i++)
183 {
184 UInt_t id = hitnum[i];
185 Int_t slice = (id>>25) & 0x7f;
186 Int_t patch = (id>>22) & 0x7;
187 UInt_t pos = id&0x3fffff;
188 AliHLTTPCSpacePointData *points = fClusters[slice][patch];
189 fXYWeight[i] = 1./ (Double_t)(points[pos].fSigmaY2 + points[pos].fSigmaY2);
190 wsum += fXYWeight[i];
191 xav += fXYWeight[i]*points[pos].fX;
192 yav += fXYWeight[i]*points[pos].fY;
193 }
194 if (fVertexConstraint == kTRUE)
195 {
196 wsum += fVertex->GetXYWeight() ;
197 xav += fVertex->GetX() ;
198 yav += fVertex->GetY() ;
199 }
200
201 xav = xav / wsum ;
202 yav = yav / wsum ;
203//
204// CALCULATE <X**2>, <XY>, AND <Y**2> WITH <X> = 0, & <Y> = 0
205//
206 Double_t xxav = 0.0 ;
207 Double_t xyav = 0.0 ;
208 Double_t yyav = 0.0 ;
209 Double_t xi, yi ;
210
211 for(Int_t i=0; i<fTrack->GetNHits(); i++)
212 {
213 UInt_t id = hitnum[i];
214 Int_t slice = (id>>25) & 0x7f;
215 Int_t patch = (id>>22) & 0x7;
216 UInt_t pos = id&0x3fffff;
217 AliHLTTPCSpacePointData *points = fClusters[slice][patch];
218
219 xi = points[pos].fX -xav;
220 yi = points[pos].fY - yav ;
221 xxav += xi * xi * fXYWeight[i];
222 xyav += xi * yi * fXYWeight[i];
223 yyav += yi * yi * fXYWeight[i];
224 }
225
226 if (fVertexConstraint == kTRUE)
227 {
228 xi = fVertex->GetX() - xav ;
229 yi = fVertex->GetY() - yav ;
230 xxav += xi * xi * fVertex->GetXYWeight() ;
231 xyav += xi * yi * fVertex->GetXYWeight() ;
232 yyav += yi * yi * fVertex->GetXYWeight() ;
233 }
234 xxav = xxav / wsum ;
235 xyav = xyav / wsum ;
236 yyav = yyav / wsum ;
237//
238//--> ROTATE COORDINATES SO THAT <XY> = 0
239//
240//--> SIGN(C**2 - S**2) = SIGN(XXAV - YYAV) >
241//--> & > ==> NEW : (XXAV-YYAV) > 0
242//--> SIGN(S) = SIGN(XYAV) >
243
244 Double_t a = fabs( xxav - yyav ) ;
245 Double_t b = 4.0 * xyav * xyav ;
246
247 Double_t asqpb = a * a + b ;
248 Double_t rasqpb = sqrt ( asqpb) ;
249
250 Double_t splus = 1.0 + a / rasqpb ;
251 Double_t sminus = b / (asqpb * splus) ;
252
253 splus = sqrt (0.5 * splus ) ;
254 sminus = sqrt (0.5 * sminus) ;
255//
256//-> FIRST REQUIRE : SIGN(C**2 - S**2) = SIGN(XXAV - YYAV)
257//
258 Double_t sinrot, cosrot ;
259 if ( xxav <= yyav ) {
260 cosrot = sminus ;
261 sinrot = splus ;
262 }
263 else {
264 cosrot = splus ;
265 sinrot = sminus ;
266 }
267//
268//-> REQUIRE : SIGN(S) = SIGN(XYAV) * SIGN(C) (ASSUMING SIGN(C) > 0)
269//
270 if ( xyav < 0.0 ) sinrot = - sinrot ;
271//
272//--> WE NOW HAVE THE SMALLEST ANGLE THAT GUARANTEES <X**2> > <Y**2>
273//--> TO GET THE SIGN OF THE CHARGE RIGHT, THE NEW X-AXIS MUST POINT
274//--> OUTWARD FROM THE ORGIN. WE ARE FREE TO CHANGE SIGNS OF BOTH
275//--> COSROT AND SINROT SIMULTANEOUSLY TO ACCOMPLISH THIS.
276//
277//--> CHOOSE SIGN OF C WISELY TO BE ABLE TO GET THE SIGN OF THE CHARGE
278//
279 if ( cosrot*xav+sinrot*yav < 0.0 ) {
280 cosrot = -cosrot ;
281 sinrot = -sinrot ;
282 }
283//
284//-> NOW GET <R**2> AND RSCALE= SQRT(<R**2>)
285//
286 Double_t rrav = xxav + yyav ;
287 Double_t rscale = sqrt(rrav) ;
288
289 xxav = 0.0 ;
290 yyav = 0.0 ;
291 xyav = 0.0 ;
292 Double_t xrrav = 0.0 ;
293 Double_t yrrav = 0.0 ;
294 Double_t rrrrav = 0.0 ;
295
296 Double_t xixi, yiyi, riri, wiriri, xold, yold ;
297
298 for(Int_t i=0; i<fTrack->GetNHits(); i++)
299 {
300 UInt_t id = hitnum[i];
301 Int_t slice = (id>>25) & 0x7f;
302 Int_t patch = (id>>22) & 0x7;
303 UInt_t pos = id&0x3fffff;
304 AliHLTTPCSpacePointData *points = fClusters[slice][patch];
305
306 xold = points[pos].fX - xav ;
307 yold = points[pos].fY - yav ;
308 //
309 //--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
310 //
311 xi = ( cosrot * xold + sinrot * yold ) / rscale ;
312 yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
313
314 xixi = xi * xi ;
315 yiyi = yi * yi ;
316 riri = xixi + yiyi ;
317 wiriri = fXYWeight[i] * riri ;
318
319 xyav += fXYWeight[i] * xi * yi ;
320 xxav += fXYWeight[i] * xixi ;
321 yyav += fXYWeight[i] * yiyi ;
322
323 xrrav += wiriri * xi ;
324 yrrav += wiriri * yi ;
325 rrrrav += wiriri * riri ;
326 }
327//
328// Include vertex if required
329//
330 if (fVertexConstraint == kTRUE)
331 {
332 xold = fVertex->GetX() - xav ;
333 yold = fVertex->GetY() - yav ;
334 //
335 //--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
336 //
337 xi = ( cosrot * xold + sinrot * yold ) / rscale ;
338 yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
339
340 xixi = xi * xi ;
341 yiyi = yi * yi ;
342 riri = xixi + yiyi ;
343 wiriri = fVertex->GetXYWeight() * riri ;
344
345 xyav += fVertex->GetXYWeight() * xi * yi ;
346 xxav += fVertex->GetXYWeight() * xixi ;
347 yyav += fVertex->GetXYWeight() * yiyi ;
348
349 xrrav += wiriri * xi ;
350 yrrav += wiriri * yi ;
351 rrrrav += wiriri * riri ;
352 }
353 //
354 //
355 //
356 //--> DIVIDE BY WSUM TO MAKE AVERAGES
357 //
358 xxav = xxav / wsum ;
359 yyav = yyav / wsum ;
360 xrrav = xrrav / wsum ;
361 yrrav = yrrav / wsum ;
362 rrrrav = rrrrav / wsum ;
363 xyav = xyav / wsum ;
364
365 Int_t const kntry = 5 ;
366//
367//--> USE THESE TO GET THE COEFFICIENTS OF THE 4-TH ORDER POLYNIMIAL
368//--> DON'T PANIC - THE THIRD ORDER TERM IS ZERO !
369//
370 Double_t xrrxrr = xrrav * xrrav ;
371 Double_t yrryrr = yrrav * yrrav ;
372 Double_t rrrrm1 = rrrrav - 1.0 ;
373 Double_t xxyy = xxav * yyav ;
374
375 Double_t c0 = rrrrm1*xxyy - xrrxrr*yyav - yrryrr*xxav ;
376 Double_t c1 = - rrrrm1 + xrrxrr + yrryrr - 4.0*xxyy ;
377 Double_t c2 = 4.0 + rrrrm1 - 4.0*xxyy ;
378 Double_t c4 = - 4.0 ;
379//
380//--> COEFFICIENTS OF THE DERIVATIVE - USED IN NEWTON-RAPHSON ITERATIONS
381//
382 Double_t c2d = 2.0 * c2 ;
383 Double_t c4d = 4.0 * c4 ;
384//
385//--> 0'TH VALUE OF LAMDA - LINEAR INTERPOLATION BETWEEN P(0) & P(YYAV)
386//
387// LAMDA = YYAV * C0 / (C0 + YRRSQ * (XXAV-YYAV))
388 Double_t lamda = 0.0 ;
389 Double_t dlamda = 0.0 ;
390//
391 Double_t chiscl = wsum * rscale * rscale ;
392 Double_t dlamax = 0.001 / chiscl ;
393
394 Double_t p, pd ;
395 for ( int itry = 1 ; itry <= kntry ; itry++ ) {
396 p = c0 + lamda * (c1 + lamda * (c2 + lamda * lamda * c4 )) ;
397 pd = (c1 + lamda * (c2d + lamda * lamda * c4d)) ;
398 dlamda = -p / pd ;
399 lamda = lamda + dlamda ;
400 if (fabs(dlamda)< dlamax) break ;
401 }
402
403 //Double_t chi2 = (Double_t)(chiscl * lamda) ;
404 //fTrack->SetChiSq1(chi2);
405 // Double_t dchisq = chiscl * dlamda ;
406 //
407 //--> NOW CALCULATE THE MATRIX ELEMENTS FOR ALPHA, BETA & KAPPA
408 //
409 Double_t h11 = xxav - lamda ;
410 Double_t h14 = xrrav ;
411 Double_t h22 = yyav - lamda ;
412 Double_t h24 = yrrav ;
413 Double_t h34 = 1.0 + 2.0*lamda ;
414 if ( h11 == 0.0 || h22 == 0.0 ){
415 LOG(AliHLTTPCLog::kError,"AliHLTTPCFitter::FitCircle","TrackFit")<<AliHLTTPCLog::kDec<<
416 "Problems fitting circle"<<ENDLOG;
417 return 1 ;
418 }
419 Double_t rootsq = (h14*h14)/(h11*h11) + 4.0*h34 ;
420
421 Double_t ratio, kappa, beta ;
422 if ( fabs(h22) > fabs(h24) ) {
423 ratio = h24 / h22 ;
424 rootsq = ratio * ratio + rootsq ;
425 kappa = 1.0 / sqrt(rootsq) ;
426 beta = - ratio * kappa ;
427 }
428 else {
429 ratio = h22 / h24 ;
430 rootsq = 1.0 + ratio * ratio * rootsq ;
431 beta = 1.0 / sqrt(rootsq) ;
432 if ( h24 > 0 ) beta = - beta ;
433 kappa = -ratio * beta ;
434 }
435 Double_t alpha = - (h14/h11) * kappa ;
436//
437//--> transform these into the lab coordinate system
438//--> first get kappa and back to real dimensions
439//
440 Double_t kappa1 = kappa / rscale ;
441 Double_t dbro = 0.5 / kappa1 ;
442//
443//--> next rotate alpha and beta and scale
444//
445 Double_t alphar = (cosrot * alpha - sinrot * beta)* dbro ;
446 Double_t betar = (sinrot * alpha + cosrot * beta)* dbro ;
447//
448//--> then translate by (xav,yav)
449//
450 Double_t acent = (double)(xav - alphar) ;
451 Double_t bcent = (double)(yav - betar ) ;
452 Double_t radius = (double)dbro ;
453//
454// Get charge
455//
456 Int_t q = ( ( yrrav < 0 ) ? 1 : -1 ) ;
457 fTrack->SetCharge(q);
458
459 //Set the first point on the track to the space point coordinates of the innermost track
460 //This will be updated to lie on the fit later on (AliHLTTPCTrack::UpdateToFirstPoint).
461 Double_t x0,y0,psi,pt ;
462 Int_t lastid=fTrack->GetNHits()-1;
463 UInt_t id = hitnum[lastid];
464 Int_t slice = (id>>25) & 0x7f;
465 Int_t patch = (id>>22) & 0x7;
466 UInt_t pos = id&0x3fffff;
467 AliHLTTPCSpacePointData *points = fClusters[slice][patch];
468 x0 = points[pos].fX;
469 y0 = points[pos].fY;
470 fTrack->SetFirstPoint(x0,y0,0); //Z-value is set in FitLine
471
472 //Set the remaining fit parameters
473 psi = (Double_t)atan2(bcent-y0,acent-x0) ;
474 psi = psi + q * 0.5F * AliHLTTPCTransform::Pi() ;
475 if ( psi < 0 ) psi = psi + 2*AliHLTTPCTransform::Pi();
476
477 pt = (Double_t)(AliHLTTPCTransform::GetBFact() * AliHLTTPCTransform::GetBField() * radius ) ;
478 fTrack->SetPsi(psi);
479 fTrack->SetPt(pt);
480 fTrack->SetRadius(radius);
481 fTrack->SetCenterX(acent);
482 fTrack->SetCenterY(bcent);
483//
484// Get errors from fast fit
485//
486 //if ( getPara()->getErrors ) getErrorsCircleFit ( acent, bcent, radius ) ;
487//
488 delete [] fXYWeight;
489 return 0 ;
490}
491
492//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
493// Fit Line in s-z plane
494//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
495Int_t AliHLTTPCFitter::FitLine ( )
496{
497 //
498 //Initialization
499 //
500 Double_t sum = 0.F ;
501 Double_t ss = 0.F ;
502 Double_t sz = 0.F ;
503 Double_t sss = 0.F ;
504 Double_t ssz = 0.F ;
505 //
506 //find sum , sums ,sumz, sumss
507 //
508 Double_t dx, dy ;
509 Double_t radius = (Double_t)(fTrack->GetPt() / ( AliHLTTPCTransform::GetBFact() * AliHLTTPCTransform::GetBField() ) ) ;
510
511 Double_t * fS = new Double_t[(fTrack->GetNHits())];
512 Double_t *fZWeight = new Double_t[fTrack->GetNHits()];
513 UInt_t *hitnum = fTrack->GetHitNumbers();
514 if (0)//fVertexConstraint==kTRUE)
515 {
516 UInt_t id = hitnum[0];
517 Int_t slice = (id>>25) & 0x7f;
518 Int_t patch = (id>>22) & 0x7;
519 UInt_t pos = id&0x3fffff;
520 AliHLTTPCSpacePointData *points = fClusters[slice][patch];
521
522 dx = points[pos].fX - fVertex->GetX();
523 dy = points[pos].fY - fVertex->GetY();
524 }
525 else
526 {
527 UInt_t id = hitnum[0];
528 Int_t slice = (id>>25) & 0x7f;
529 Int_t patch = (id>>22) & 0x7;
530 UInt_t posf = id&0x3fffff;
531 AliHLTTPCSpacePointData *pointsf = fClusters[slice][patch];
532 id = hitnum[(fTrack->GetNHits()-1)];
533 slice = (id>>25) & 0x7f;
534 patch = (id>>22) & 0x7;
535 UInt_t posl = id&0x3fffff;
536 AliHLTTPCSpacePointData *pointsl = fClusters[slice][patch];
537 dx = pointsf[posf].fX - pointsl[posl].fX;
538 dy = pointsf[posf].fY - pointsl[posl].fY;
539 }
540
541 Double_t localPsi = 0.5F * sqrt ( dx*dx + dy*dy ) / radius ;
542 Double_t totals ;
543
544 if ( fabs(localPsi) < 1. )
545 {
546 totals = 2.0 * radius * asin ( localPsi ) ;
547 }
548 else
549 {
550 totals = 2.0 * radius * AliHLTTPCTransform::Pi() ;
551 }
552
553 Double_t dpsi,s;
554
555 for(Int_t i=0; i<fTrack->GetNHits(); i++)
556 {
557 UInt_t id = hitnum[i];
558 Int_t slice = (id>>25) & 0x7f;
559 Int_t patch = (id>>22) & 0x7;
560 UInt_t pos = id&0x3fffff;
561 AliHLTTPCSpacePointData *points = fClusters[slice][patch];
562
563 fZWeight[i] = 1./(Double_t)(points[pos].fSigmaZ2);
564 if(i>0)
565 {
566 id = hitnum[i-1];
567 slice = (id>>25) & 0x7f;
568 patch = (id>>22) & 0x7;
569 UInt_t lastpos = id&0x3fffff;
570 AliHLTTPCSpacePointData *lastpoints = fClusters[slice][patch];
571 dx = points[pos].fX -lastpoints[lastpos].fX;
572 dy = points[pos].fY -lastpoints[lastpos].fY;
573 dpsi = 0.5 * (Double_t)sqrt ( dx*dx + dy*dy ) / radius ;
574 if(fabs(dpsi) > 1)
575 return 1;
576 fTrack->SetPsierr(dpsi);
577 s = fS[i-1] - 2.0 * radius * (Double_t)asin ( dpsi ) ;
578 fS[i]=s;
579 }
580 else
581 fS[i]=totals;
582
583 sum += fZWeight[i];
584 ss += fZWeight[i] * fS[i];
585 sz += fZWeight[i] * points[pos].fZ;
586 sss += fZWeight[i] * fS[i] * fS[i];
587 ssz += fZWeight[i] * fS[i] * points[pos].fZ;
588
589 }
590
591
592 Double_t chi2,det = sum * sss - ss * ss;
593 if ( fabs(det) < 1e-20)
594 {
595 chi2 = 99999.F ;
596 //fTrack->SetChiSq2(chi2);
597 return 0 ;
598 }
599
600 //Compute the best fitted parameters A,B
601 Double_t tanl,z0,dtanl,dz0;
602
603 tanl = (Double_t)((sum * ssz - ss * sz ) / det );
604 z0 = (Double_t)((sz * sss - ssz * ss ) / det );
605
606 fTrack->SetTgl(tanl);
607 fTrack->SetZ0(z0);
608
609 //calculate chi-square
610 chi2 = 0.;
611 Double_t r1 ;
612
613 for(Int_t i=0; i<fTrack->GetNHits(); i++)
614 {
615 UInt_t id = hitnum[i];
616 Int_t slice = (id>>25) & 0x7f;
617 Int_t patch = (id>>22) & 0x7;
618 UInt_t pos = id&0x3fffff;
619 AliHLTTPCSpacePointData *points = fClusters[slice][patch];
620 r1 = points[pos].fZ - tanl * fS[i] - z0 ;
621 chi2 += (Double_t) ( (Double_t)(fZWeight[i]) * (r1 * r1) );
622 }
623
624 //fTrack->SetChiSq2(chi2);
625 //
626 //calculate estimated variance
627 //varsq=chi/(double(n)-2.)
628 //calculate covariance matrix
629 //siga=sqrt(varsq*sxx/det)
630 //sigb=sqrt(varsq*sum/det)
631 //
632 dtanl = (Double_t) ( sum / det );
633 dz0 = (Double_t) ( sss / det );
634
635 fTrack->SetTglerr(dtanl);
636 fTrack->SetZ0err(dz0);
637 delete [] fZWeight;
638 delete [] fS;
639 return 0 ;
640}