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a6c02c85 1// @(#) $Id$
4aa41877 2// Original: AliHLTConfMapFit.cxx,v 1.14 2005/06/14 10:55:21 cvetan
a6c02c85 3
2a083ac4 4/**************************************************************************
9be2600f 5 * This file is property of and copyright by the ALICE HLT Project *
6 * ALICE Experiment at CERN, All rights reserved. *
2a083ac4 7 * *
9be2600f 8 * Primary Authors: Anders Vestbo, maintained by *
9 * Matthias Richter <Matthias.Richter@ift.uib.no> *
10 * for The ALICE HLT Project. *
2a083ac4 11 * *
12 * Permission to use, copy, modify and distribute this software and its *
13 * documentation strictly for non-commercial purposes is hereby granted *
14 * without fee, provided that the above copyright notice appears in all *
15 * copies and that both the copyright notice and this permission notice *
16 * appear in the supporting documentation. The authors make no claims *
17 * about the suitability of this software for any purpose. It is *
18 * provided "as is" without express or implied warranty. *
19 **************************************************************************/
20
21/** @file AliHLTTPCConfMapFit.cxx
22 @author Anders Vestbo, maintained by Matthias Richter
23 @date
24 @brief Fit class for conformal mapping tracking.
25*/
a6c02c85 26
e67b0680 27// see header file for class documentation //
28// or //
29// refer to README to build package //
30// or //
31// visit http://web.ift.uib.no/~kjeks/doc/alice-hlt //
32
a6c02c85 33#include "AliHLTTPCRootTypes.h"
34#include "AliHLTTPCLogging.h"
35#include "AliHLTTPCVertex.h"
36#include "AliHLTTPCConfMapTrack.h"
37#include "AliHLTTPCConfMapPoint.h"
38#include "AliHLTTPCTransform.h"
39#include "AliHLTTPCConfMapFit.h"
40
a6c02c85 41#if __GNUC__ >= 3
42using namespace std;
43#endif
44
e67b0680 45ClassImp(AliHLTTPCConfMapFit);
a6c02c85 46
2a083ac4 47AliHLTTPCConfMapFit::AliHLTTPCConfMapFit()
48 :
49 fTrack(NULL),
50 fVertex(NULL)
51{
52 //constructor
53}
54
a6c02c85 55AliHLTTPCConfMapFit::AliHLTTPCConfMapFit(AliHLTTPCConfMapTrack *track,AliHLTTPCVertex *vertex)
2a083ac4 56 :
57 fTrack(track),
58 fVertex(vertex)
59
a6c02c85 60{
61 //constructor
2a083ac4 62}
63
2a083ac4 64AliHLTTPCConfMapFit::~AliHLTTPCConfMapFit()
65{
66 // destructor
a6c02c85 67}
68
69Int_t AliHLTTPCConfMapFit::FitHelix()
70{
71 //fit the helix
72 if(FitCircle())
73 {
74 LOG(AliHLTTPCLog::kError,"AliHLTTPCConfMapFit::FitHelix","TrackFit")<<AliHLTTPCLog::kDec<<
75 "Problems during circle fit"<<ENDLOG;
76 return 1;
77 }
78 if(FitLine())
79 {
80 LOG(AliHLTTPCLog::kError,"AliHLTTPCConfMapFit::FitHelix","TrackFit")<<AliHLTTPCLog::kDec<<
81 "Problems during line fit"<<ENDLOG;
82 return 1;
83 }
84 return 0;
85}
86
db16520a 87Int_t AliHLTTPCConfMapFit::FitStraightLine() {
88 //fit the straight line
89 if(FitLineXY()) {
90 LOG(AliHLTTPCLog::kError,"AliHLTTPCConfMapFit::FitStraightLine","TrackFit")<<AliHLTTPCLog::kDec<<
91 "Problems during stright line fit in XY plane"<<ENDLOG;
92 return 1;
93 }
94 if(FitLineSZ()){
95 LOG(AliHLTTPCLog::kError,"AliHLTTPCConfMapFit::FitStraightLine","TrackFit")<<AliHLTTPCLog::kDec<<
96 "Problems during stright line fit in SZ plane"<<ENDLOG;
97 return 1;
98 }
99 return 0;
100}
101
a6c02c85 102Int_t AliHLTTPCConfMapFit::FitCircle()
103{
104 //-----------------------------------------------------------------
105 //Fits circle parameters using algorithm
106 //described by ChErnov and Oskov in Computer Physics
107 //Communications.
108 //
109 //Written in FORTRAN by Jawluen Tang, Physics department , UT-Austin
110 //Moved to C by Pablo Yepes
111 //Moved to AliROOT by ASV.
112 //------------------------------------------------------------------
113
114 Double_t wsum = 0.0 ;
115 Double_t xav = 0.0 ;
116 Double_t yav = 0.0 ;
117
e67b0680 118 Int_t numOfHits = fTrack->GetNumberOfPoints();
a6c02c85 119 //
120 // Loop over hits calculating average
121 Int_t co=0;
122
123 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
124 {
125 co++;
126 AliHLTTPCConfMapPoint *cHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
127 cHit->SetXYWeight( 1./ (Double_t)(cHit->GetXerr()*cHit->GetXerr() + cHit->GetYerr()*cHit->GetYerr()) );
128 wsum += cHit->GetXYWeight() ;
129 xav += cHit->GetXYWeight() * cHit->GetX() ;
130 yav += cHit->GetXYWeight() * cHit->GetY() ;
131 }
e67b0680 132 if(co!=numOfHits)
a6c02c85 133 LOG(AliHLTTPCLog::kError,"AliHLTTPCConfMapFit::FitCircle","TrackFit")<<AliHLTTPCLog::kDec<<
e67b0680 134 "Mismatch of hits. Counter: "<<co<<" nHits: "<<numOfHits<<ENDLOG;
a6c02c85 135 if (fTrack->ComesFromMainVertex() == true)
136 {
137 wsum += fVertex->GetXYWeight() ;
138 xav += fVertex->GetX() ;
139 yav += fVertex->GetY() ;
140 }
141
142 xav = xav / wsum ;
143 yav = yav / wsum ;
144//
145// CALCULATE <X**2>, <XY>, AND <Y**2> WITH <X> = 0, & <Y> = 0
146//
147 Double_t xxav = 0.0 ;
148 Double_t xyav = 0.0 ;
149 Double_t yyav = 0.0 ;
150 Double_t xi, yi ;
151
152 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
153 {
154 //AliHLTTPCConfMapPoint *cHit = (AliHLTTPCConfMapPoint *)hits->At(hit_counter);
155 AliHLTTPCConfMapPoint *cHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
156 xi = cHit->GetX() - xav ;
157 yi = cHit->GetY() - yav ;
158 xxav += xi * xi * cHit->GetXYWeight() ;
159 xyav += xi * yi * cHit->GetXYWeight() ;
160 yyav += yi * yi * cHit->GetXYWeight() ;
161 }
162
163 if (fTrack->ComesFromMainVertex() == true)
164 {
165 xi = fVertex->GetX() - xav ;
166 yi = fVertex->GetY() - yav ;
167 xxav += xi * xi * fVertex->GetXYWeight() ;
168 xyav += xi * yi * fVertex->GetXYWeight() ;
169 yyav += yi * yi * fVertex->GetXYWeight() ;
170 }
171 xxav = xxav / wsum ;
172 xyav = xyav / wsum ;
173 yyav = yyav / wsum ;
174//
175//--> ROTATE COORDINATES SO THAT <XY> = 0
176//
177//--> SIGN(C**2 - S**2) = SIGN(XXAV - YYAV) >
178//--> & > ==> NEW : (XXAV-YYAV) > 0
179//--> SIGN(S) = SIGN(XYAV) >
180
181 Double_t a = fabs( xxav - yyav ) ;
182 Double_t b = 4.0 * xyav * xyav ;
183
184 Double_t asqpb = a * a + b ;
185 Double_t rasqpb = sqrt ( asqpb) ;
186
187 Double_t splus = 1.0 + a / rasqpb ;
188 Double_t sminus = b / (asqpb * splus) ;
189
190 splus = sqrt (0.5 * splus ) ;
191 sminus = sqrt (0.5 * sminus) ;
192//
193//-> FIRST REQUIRE : SIGN(C**2 - S**2) = SIGN(XXAV - YYAV)
194//
195 Double_t sinrot, cosrot ;
196 if ( xxav <= yyav ) {
197 cosrot = sminus ;
198 sinrot = splus ;
199 }
200 else {
201 cosrot = splus ;
202 sinrot = sminus ;
203 }
204//
205//-> REQUIRE : SIGN(S) = SIGN(XYAV) * SIGN(C) (ASSUMING SIGN(C) > 0)
206//
207 if ( xyav < 0.0 ) sinrot = - sinrot ;
208//
209//--> WE NOW HAVE THE SMALLEST ANGLE THAT GUARANTEES <X**2> > <Y**2>
210//--> TO GET THE SIGN OF THE CHARGE RIGHT, THE NEW X-AXIS MUST POINT
211//--> OUTWARD FROM THE ORGIN. WE ARE FREE TO CHANGE SIGNS OF BOTH
212//--> COSROT AND SINROT SIMULTANEOUSLY TO ACCOMPLISH THIS.
213//
214//--> CHOOSE SIGN OF C WISELY TO BE ABLE TO GET THE SIGN OF THE CHARGE
215//
216 if ( cosrot*xav+sinrot*yav < 0.0 ) {
217 cosrot = -cosrot ;
218 sinrot = -sinrot ;
219 }
220//
221//-> NOW GET <R**2> AND RSCALE= SQRT(<R**2>)
222//
223 Double_t rrav = xxav + yyav ;
224 Double_t rscale = sqrt(rrav) ;
225
226 xxav = 0.0 ;
227 yyav = 0.0 ;
228 xyav = 0.0 ;
229 Double_t xrrav = 0.0 ;
230 Double_t yrrav = 0.0 ;
231 Double_t rrrrav = 0.0 ;
232
233 Double_t xixi, yiyi, riri, wiriri, xold, yold ;
234
e67b0680 235 //for (hit_counter=0; hit_counter<numOfHits; hit_counter++)
a6c02c85 236 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
237 {
238 //AliHLTTPCConfMapPoint *cHit = (AliHLTTPCConfMapPoint*)hits->At(hit_counter);
239 AliHLTTPCConfMapPoint* cHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
240
241 xold = cHit->GetX() - xav ;
242 yold = cHit->GetY() - yav ;
243 //
244 //--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
245 //
246 xi = ( cosrot * xold + sinrot * yold ) / rscale ;
247 yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
248
249 xixi = xi * xi ;
250 yiyi = yi * yi ;
251 riri = xixi + yiyi ;
252 wiriri = cHit->GetXYWeight() * riri ;
253
254 xyav += cHit->GetXYWeight() * xi * yi ;
255 xxav += cHit->GetXYWeight() * xixi ;
256 yyav += cHit->GetXYWeight() * yiyi ;
257
258 xrrav += wiriri * xi ;
259 yrrav += wiriri * yi ;
260 rrrrav += wiriri * riri ;
261 }
262 //
263// Include vertex if required
264//
265 if (fTrack->ComesFromMainVertex() == true)
266 {
267 xold = fVertex->GetX() - xav ;
268 yold = fVertex->GetY() - yav ;
269 //
270 //--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
271 //
272 xi = ( cosrot * xold + sinrot * yold ) / rscale ;
273 yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
274
275 xixi = xi * xi ;
276 yiyi = yi * yi ;
277 riri = xixi + yiyi ;
278 wiriri = fVertex->GetXYWeight() * riri ;
279
280 xyav += fVertex->GetXYWeight() * xi * yi ;
281 xxav += fVertex->GetXYWeight() * xixi ;
282 yyav += fVertex->GetXYWeight() * yiyi ;
283
284 xrrav += wiriri * xi ;
285 yrrav += wiriri * yi ;
286 rrrrav += wiriri * riri ;
287 }
288 //
289 //
290 //
291 //--> DIVIDE BY WSUM TO MAKE AVERAGES
292 //
293 xxav = xxav / wsum ;
294 yyav = yyav / wsum ;
295 xrrav = xrrav / wsum ;
296 yrrav = yrrav / wsum ;
297 rrrrav = rrrrav / wsum ;
298 xyav = xyav / wsum ;
299
e67b0680 300 const Int_t ntry = 5 ;
a6c02c85 301//
302//--> USE THESE TO GET THE COEFFICIENTS OF THE 4-TH ORDER POLYNIMIAL
303//--> DON'T PANIC - THE THIRD ORDER TERM IS ZERO !
304//
305 Double_t xrrxrr = xrrav * xrrav ;
306 Double_t yrryrr = yrrav * yrrav ;
307 Double_t rrrrm1 = rrrrav - 1.0 ;
308 Double_t xxyy = xxav * yyav ;
309
310 Double_t c0 = rrrrm1*xxyy - xrrxrr*yyav - yrryrr*xxav ;
311 Double_t c1 = - rrrrm1 + xrrxrr + yrryrr - 4.0*xxyy ;
312 Double_t c2 = 4.0 + rrrrm1 - 4.0*xxyy ;
313 Double_t c4 = - 4.0 ;
314//
315//--> COEFFICIENTS OF THE DERIVATIVE - USED IN NEWTON-RAPHSON ITERATIONS
316//
317 Double_t c2d = 2.0 * c2 ;
318 Double_t c4d = 4.0 * c4 ;
319//
320//--> 0'TH VALUE OF LAMDA - LINEAR INTERPOLATION BETWEEN P(0) & P(YYAV)
321//
322// LAMDA = YYAV * C0 / (C0 + YRRSQ * (XXAV-YYAV))
323 Double_t lamda = 0.0 ;
324 Double_t dlamda = 0.0 ;
325//
326 Double_t chiscl = wsum * rscale * rscale ;
327 Double_t dlamax = 0.001 / chiscl ;
328
329 Double_t p, pd ;
330 for ( int itry = 1 ; itry <= ntry ; itry++ ) {
331 p = c0 + lamda * (c1 + lamda * (c2 + lamda * lamda * c4 )) ;
332 pd = (c1 + lamda * (c2d + lamda * lamda * c4d)) ;
333 dlamda = -p / pd ;
334 lamda = lamda + dlamda ;
335 if (fabs(dlamda)< dlamax) break ;
336 }
337
338 Double_t chi2 = (Double_t)(chiscl * lamda) ;
339
340 fTrack->SetChiSq1(chi2);
341 // Double_t dchisq = chiscl * dlamda ;
342//
343//--> NOW CALCULATE THE MATRIX ELEMENTS FOR ALPHA, BETA & KAPPA
344//
345 Double_t h11 = xxav - lamda ;
346 Double_t h14 = xrrav ;
347 Double_t h22 = yyav - lamda ;
348 Double_t h24 = yrrav ;
349 Double_t h34 = 1.0 + 2.0*lamda ;
350 if ( h11 == 0.0 || h22 == 0.0 ){
351 LOG(AliHLTTPCLog::kError,"AliHLTTPCConfMapFit::FitCircle","TrackFit")<<AliHLTTPCLog::kDec<<
352 "Problems fitting circle"<<ENDLOG;
353 return 1 ;
354 }
355 Double_t rootsq = (h14*h14)/(h11*h11) + 4.0*h34 ;
356
357 Double_t ratio, kappa, beta ;
358 if ( fabs(h22) > fabs(h24) ) {
359 ratio = h24 / h22 ;
360 rootsq = ratio * ratio + rootsq ;
361 kappa = 1.0 / sqrt(rootsq) ;
362 beta = - ratio * kappa ;
363 }
364 else {
365 ratio = h22 / h24 ;
366 rootsq = 1.0 + ratio * ratio * rootsq ;
367 beta = 1.0 / sqrt(rootsq) ;
368 if ( h24 > 0 ) beta = - beta ;
369 kappa = -ratio * beta ;
370 }
371 Double_t alpha = - (h14/h11) * kappa ;
372//
373//--> transform these into the lab coordinate system
374//--> first get kappa and back to real dimensions
375//
376 Double_t kappa1 = kappa / rscale ;
377 Double_t dbro = 0.5 / kappa1 ;
378//
379//--> next rotate alpha and beta and scale
380//
381 Double_t alphar = (cosrot * alpha - sinrot * beta)* dbro ;
382 Double_t betar = (sinrot * alpha + cosrot * beta)* dbro ;
383//
384//--> then translate by (xav,yav)
385//
386 Double_t acent = (double)(xav - alphar) ;
387 Double_t bcent = (double)(yav - betar ) ;
388 Double_t radius = (double)dbro ;
389//
390// Get charge
391//
392 Int_t q = ( ( yrrav < 0 ) ? 1 : -1 ) ;
393
394 fTrack->SetCharge(q);
395
396
397 //Set the first point on the track to the space point coordinates of the innermost track
398 //This will be updated to lie on the fit later on (AliHLTTPCTrack::UpdateToFirstPoint).
399 Double_t x0,y0,psi,pt ;
400 AliHLTTPCConfMapPoint *lHit = (AliHLTTPCConfMapPoint*)fTrack->GetLastHit();
401 x0 = lHit->GetX();
402 y0 = lHit->GetY();
403 fTrack->SetFirstPoint(x0,y0,0); //Z-value is set in FitLine
404
405 psi = (Double_t)atan2(bcent-y0,acent-x0) ;
406 psi = psi + q * AliHLTTPCTransform::PiHalf();
407 if ( psi < 0 ) psi = psi + AliHLTTPCTransform::TwoPi();
408 pt = (Double_t)(AliHLTTPCTransform::GetBFieldValue() * radius ) ;
409
410 //Update the track parameters with the parameters from this fit:
411 fTrack->SetPsi(psi);
412 fTrack->SetPt(pt);
413 fTrack->SetRadius(radius);
414 fTrack->SetCenterX(acent);
415 fTrack->SetCenterY(bcent);
416
1ee9dca4 417 fTrack->SetY0err(0.03);
31f11c63 418 //set error for pT and Y. psi, Z and Tgl are set.
419
a6c02c85 420 //
421// Get errors from fast fit
422//
423 //if ( getPara()->getErrors ) getErrorsCircleFit ( acent, bcent, radius ) ;
424//
425 return 0 ;
426
427}
428
429//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
430// Fit Line in s-z plane
431//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
432Int_t AliHLTTPCConfMapFit::FitLine ( )
433{
434 //
435 //Initialization
436 //
437 Double_t sum = 0.F ;
438 Double_t ss = 0.F ;
439 Double_t sz = 0.F ;
440 Double_t sss = 0.F ;
441 Double_t ssz = 0.F ;
442 //
443 //find sum , sums ,sumz, sumss
444 //
445 Double_t dx, dy ;
446 Double_t radius = (Double_t)(fTrack->GetPt() / AliHLTTPCTransform::GetBFieldValue() ) ;
447
448 //TObjArray *hits = fTrack->GetHits();
e67b0680 449 //Int_t numOfHits = fTrack->GetNumberOfPoints();
a6c02c85 450
451 if (0)// fTrack->ComesFromMainVertex() == true )
452 {
453 dx = ((AliHLTTPCConfMapPoint*)fTrack->GetFirstHit())->GetX() - fVertex->GetX();
454 dy = ((AliHLTTPCConfMapPoint*)fTrack->GetFirstHit())->GetY() - fVertex->GetY() ;
455 }
456 else
457 {
458 dx = ((AliHLTTPCConfMapPoint *)fTrack->GetFirstHit())->GetX() - ((AliHLTTPCConfMapPoint *)fTrack->GetLastHit())->GetX() ;
459 dy = ((AliHLTTPCConfMapPoint *)fTrack->GetFirstHit())->GetY() - ((AliHLTTPCConfMapPoint *)fTrack->GetLastHit())->GetY() ;
460 //dx = ((AliHLTTPCConfMapPoint *)hits->First())->GetX() - ((AliHLTTPCConfMapPoint *)hits->Last())->GetX() ;
461 //dy = ((AliHLTTPCConfMapPoint *)hits->First())->GetY() - ((AliHLTTPCConfMapPoint *)hits->Last())->GetY() ;
462 }
463
464 Double_t localPsi = 0.5F * sqrt ( dx*dx + dy*dy ) / radius ;
e67b0680 465 Double_t totalS ;
a6c02c85 466
467 if ( fabs(localPsi) < 1. )
468 {
e67b0680 469 totalS = 2.0 * radius * asin ( localPsi ) ;
a6c02c85 470 }
471 else
472 {
e67b0680 473 totalS = 2.0 * radius * AliHLTTPCTransform::Pi() ;
a6c02c85 474 }
475
476 AliHLTTPCConfMapPoint *previousHit = NULL;
477
478 // FtfBaseHit *previousHit = 0 ;
479
480 //for ( startLoop() ; done() ; nextHit() ) {
481 Double_t dpsi,s;
482
e67b0680 483 // for(hit_counter=0; hit_counter<numOfHits; hit_counter++)
a6c02c85 484 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
485 {
486 // AliHLTTPCConfMapPoint *cHit = (AliHLTTPCConfMapPoint*)hits->At(hit_counter);
487 AliHLTTPCConfMapPoint *cHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
488 // if ( GetCurrentHit() != GetFirstHit() )
8fb3f728 489 if(previousHit)// hits->First())
a6c02c85 490 {
8fb3f728 491 // this means cHit != fTrack->GetFirstHit()
a6c02c85 492 dx = cHit->GetX() - previousHit->GetX() ;
493 dy = cHit->GetY() - previousHit->GetY() ;
494 dpsi = 0.5 * (Double_t)sqrt ( dx*dx + dy*dy ) / radius ;
495 fTrack->SetPsierr(dpsi);
496 s = previousHit->GetS() - 2.0 * radius * (Double_t)asin ( dpsi ) ;
497 cHit->SetS(s);
498 }
499 else
e67b0680 500 cHit->SetS(totalS);
501 // cHit->s = totalS ;
a6c02c85 502
503 sum += cHit->GetZWeight() ;
504 ss += cHit->GetZWeight() * cHit->GetS() ;
505 sz += cHit->GetZWeight() * cHit->GetZ() ;
506 sss += cHit->GetZWeight() * cHit->GetS() * cHit->GetS() ;
507 ssz += cHit->GetZWeight() * cHit->GetS() * cHit->GetZ() ;
508 previousHit = cHit ;
509 }
510
511 Double_t chi2,det = sum * sss - ss * ss;
512 if ( fabs(det) < 1e-20)
513 {
514 chi2 = 99999.F ;
515 fTrack->SetChiSq2(chi2);
516 return 0 ;
517 }
518
519 //Compute the best fitted parameters A,B
520 Double_t tanl,z0,dtanl,dz0;
521
522 tanl = (Double_t)((sum * ssz - ss * sz ) / det );
523 z0 = (Double_t)((sz * sss - ssz * ss ) / det );
524
525 fTrack->SetTgl(tanl);
526 fTrack->SetZ0(z0);
527
528 // calculate chi-square
529
530 chi2 = 0.;
531 Double_t r1 ;
532
e67b0680 533 //for(hit_counter=0; hit_counter<numOfHits; hit_counter++)
a6c02c85 534 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
535 {
536 //AliHLTTPCConfMapPoint *cHit = (AliHLTTPCConfMapPoint*)hits->At(hit_counter);
537 AliHLTTPCConfMapPoint *cHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
538 r1 = cHit->GetZ() - tanl * cHit->GetS() - z0 ;
539 chi2 += (Double_t) ( (Double_t)cHit->GetZWeight() * (r1 * r1) );
540 }
541 fTrack->SetChiSq2(chi2);
542 //
543 // calculate estimated variance
544 // varsq=chi/(double(n)-2.)
545 // calculate covariance matrix
546 // siga=sqrt(varsq*sxx/det)
547 // sigb=sqrt(varsq*sum/det)
548 //
549 dtanl = (Double_t) ( sum / det );
550 dz0 = (Double_t) ( sss / det );
551
552 fTrack->SetTglerr(dtanl);
553 fTrack->SetZ0err(dz0);
1ee9dca4 554
555 //The calculation of pT comes from "Perticle Physics Booklet":
556 //24.11 Measurement of particle momenta in a uniform magnetic field.
557 //(dk)^2=(dk_res)^2 + (dk_ms)^2
558 //for now k_ms is 0. Need to find length of track in 3D.
559
560 Double_t lengthXY = fTrack->GetLengthXY();
561 //Double_t lengthTot = fTrack->GetLengthTot();
562 //Double_t beta = fTrack->GetP()/TMath::Sqrt((fTrack->GetP()*fTrack->GetP())+(0.13957*0.13957));
563 //Double_t lambda = TMath::ATan(fTrack->GetTgl());
564 Double_t lengthXY2 = lengthXY*lengthXY;
565 Int_t nCluster4 = fTrack->GetNHits()+4;
566
567 Double_t Kres = 0.03/lengthXY2;
568 Kres = Kres * TMath::Sqrt(720/nCluster4);
569
570 //Double_t Kres = (0.03/(lengthXY*lengthXY))*TMath::Sqrt(720/(fTrack->GetNHits()+4));
571
572 //Double_t d = lengthTot*fTrack->GetP()*beta*TMath::Cos(lambda)*TMath::Cos(lambda);
573 //Double_t Kms = (0.016/d)*TMath::Sqrt(lengthTot/24.0);
574 Double_t Kms = 0.0;
575
ec75ebfe 576 Double_t KTot = TMath::Sqrt((Kres * Kres) + (Kms * Kms));
577
578 Double_t Pterr = (1/(0.3*AliHLTTPCTransform::GetBField()))*KTot;
1ee9dca4 579
580 fTrack->SetPterr(Pterr);
581
a6c02c85 582 return 0 ;
583}
db16520a 584
585
db16520a 586//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
587// Straight Line Fit in x-y plane
588//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
589Int_t AliHLTTPCConfMapFit::FitLineXY ( ){
590 // -----------------------------------------------------------------------------
591 // Implementation after Numerical Recipes in C, 2nd Edtion, chapter 15.2, p. 661
592 // with y = b*x + a
593 // and Data Analysis for Physical Science Students, Luis Lyons, chapter 2.4 p.51
594 // with y = a' + bx' , x' = x - <x>
595 // -----------------------------------------------------------------------------
596
e67b0680 597 Double_t s = 0.;
598 Double_t sx = 0.;
db16520a 599
e67b0680 600 Double_t sPrime = 0.;
601 Double_t sxPrime = 0.;
602 Double_t sxxPrime = 0.;
603 Double_t syPrime = 0.;
604 Double_t sxyPrime = 0.;
db16520a 605
606 Double_t chi2 = 0.;
607
e67b0680 608 Int_t numOfHits = fTrack->GetNumberOfPoints();
db16520a 609
610 Int_t co=0;
611
612 // - Loop over hits calculating average : xav
613 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit()) {
614 co++;
615 AliHLTTPCConfMapPoint *currentHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
616 // ** maybe not necessary, already done in ConfMapPoint
617 currentHit->SetXYWeight( 1./ (Double_t)(currentHit->GetXerr()*currentHit->GetXerr() + currentHit->GetYerr()*currentHit->GetYerr()) );
618 // **
e67b0680 619 s += currentHit->GetXYWeight();
620 sx += currentHit->GetXYWeight() * currentHit->GetX();
db16520a 621 }
622
e67b0680 623 if(co!=numOfHits)
624 LOG(AliHLTTPCLog::kError,"AliHLTTPCConfMapFit::FitLineXY","TrackFit") << "Mismatch of hits. Counter: "<<co<<" nHits: "<<numOfHits<<ENDLOG;
db16520a 625
e67b0680 626 Double_t xav = (Double_t)sx / s;
db16520a 627
628 // Calculate weighted means
629 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit()) {
630 AliHLTTPCConfMapPoint *currentHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
631
632 Double_t xPrime = currentHit->GetX() - xav;
e67b0680 633 sPrime += currentHit->GetXYWeight();
634 sxPrime += currentHit->GetXYWeight() * xPrime;
635 sxxPrime += currentHit->GetXYWeight() * xPrime * xPrime;
636 syPrime += currentHit->GetXYWeight() * currentHit->GetY();
637 sxyPrime += currentHit->GetXYWeight() * xPrime * currentHit->GetY();
db16520a 638 }
639
e67b0680 640 Double_t det = sPrime*sxxPrime + sxPrime*sxPrime;
db16520a 641
642 if (fabs(det) < 1e-20) {
643 LOG(AliHLTTPCLog::kDebug,"AliHLTTPCConfMapFit::FitLineXY","TrackFit") << "Determinant == 0" << ENDLOG;
644 chi2 = 99999.F ;
645 fTrack->SetChiSq1(chi2);
646 return -1 ;
647 }
648
e67b0680 649 Double_t b = (Double_t)(sPrime*sxyPrime - sxPrime*syPrime) / det; // line parameter b
650 Double_t aPrime = (Double_t)(sxxPrime*syPrime - sxPrime*sxyPrime) / det; // line parameter a
db16520a 651
e67b0680 652 Double_t sigma2b = (Double_t)1. / sxxPrime;
653 //-- Double_t sigma2aprime = (Double_t)1. /sPrime;
db16520a 654
655 // Get gradient angle psi of line in xy plane
656 Double_t psi = (Double_t) atan(b) ;
657
658 // Calculate chi2
659 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit()) {
660 AliHLTTPCConfMapPoint *currentHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
661 Double_t tempchi = currentHit->GetY() - aPrime - b*(currentHit->GetX() - xav);
662 chi2 += tempchi*tempchi*currentHit->GetXYWeight() ;
663 }
664
665 Double_t a = aPrime - b*xav;
666
667
668 // Set TrackParameter
669 fTrack->SetChiSq1(chi2);
670 fTrack->SetPsi(psi);
671 fTrack->SetPsierr(sigma2b);
672 fTrack->SetCenterX(0.); // Set to point on the track (for UpdateToFirstPoint)
673 fTrack->SetCenterY(a); // Set to point on the track (for UpdateToFirstPoint)
674
675 //Set the first point on the track to the space point coordinates of the innermost track
676 //This will be updated to lie on the fit later on (AliHLTTPCTrack::UpdateToFirstPoint).
677 AliHLTTPCConfMapPoint *lastHit = (AliHLTTPCConfMapPoint*)fTrack->GetLastHit();
678 Double_t x0 = lastHit->GetX();
679 Double_t y0 = lastHit->GetY();
680 fTrack->SetFirstPoint(x0,y0,0); //Z-value is set in FitLineSZ
681
682
683 //Set Defaults
684 fTrack->SetRadius(-1.);
685 fTrack->SetCharge(1);
686 fTrack->SetPt(-1.);
687
688
689 return 0;
690}
691
692
693//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
694// Straight Line Fit in s-z plane
695//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
696Int_t AliHLTTPCConfMapFit::FitLineSZ ( ){
697 // -----------------------------------------------------------------------------
698 // Implementation after Numerical Recipes in C, 2nd Edtion, chapter 15.2, p. 661
699 // with z = b*s + a
700 // and Data Analysis for Physical Science Students, Luis Lyons, chapter 2.4 p.51
701 // with z = a' + bs' , s' = s - <s>
702 // -----------------------------------------------------------------------------
703
704 Double_t S = 0.;
705 Double_t Ss = 0.;
706
e67b0680 707 Double_t sPrime = 0.;
708 Double_t ssPrime = 0.;
709 Double_t sssPrime = 0.;
710 Double_t szPrime = 0.;
711 Double_t sszPrime = 0.;
db16520a 712
713 Double_t chi2 = 0.;
e67b0680 714
715 // Matthias 16.10.2007
716 // what's that!!! local variables 's' and 'S'
717 // change Double_t s = 0.; -> slength
718 Double_t slength = 0.;
db16520a 719
8fb3f728 720 // Matthias 23.02.2011
721 // this looks like a bug: previousHit is initialized, not changed
722 // in the loop, but dereferenced for all but the first hit
723 // changing the condition and adding an assignment at the end
724 // of the loop
db16520a 725 AliHLTTPCConfMapPoint *previousHit = NULL;
726
727 // - Loop over hits calculating length in xy-plane: s
728 // - Loop over hits calculating average : sav
729 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit()) {
730 AliHLTTPCConfMapPoint *currentHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
8fb3f728 731 if(previousHit) {
732 // this means currentHit != fTrack->GetFirstHit()
db16520a 733 Double_t dx = currentHit->GetX() - previousHit->GetX() ;
734 Double_t dy = currentHit->GetY() - previousHit->GetY() ;
e67b0680 735 slength = previousHit->GetS() - (Double_t)sqrt ( dx*dx + dy*dy );
db16520a 736 }
737 else{
738 Double_t dx = ((AliHLTTPCConfMapPoint *)fTrack->GetFirstHit())->GetX() - ((AliHLTTPCConfMapPoint *)fTrack->GetLastHit())->GetX();
739 Double_t dy = ((AliHLTTPCConfMapPoint *)fTrack->GetFirstHit())->GetY() - ((AliHLTTPCConfMapPoint *)fTrack->GetLastHit())->GetY();
e67b0680 740 slength = (Double_t)sqrt ( dx*dx + dy*dy );
db16520a 741 }
742
e67b0680 743 currentHit->SetS(slength);
db16520a 744
745 S += currentHit->GetZWeight();
746 Ss += currentHit->GetZWeight() * currentHit->GetS();
8fb3f728 747
748 // Matthias 23.02.2011
749 // adding missing assignment, otherwise previousHit stays NULL
750 previousHit=currentHit;
db16520a 751 }
752
753 Double_t sav = (Double_t)Ss / S;
754
755 // Calculate weighted means
756 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit()) {
757 AliHLTTPCConfMapPoint *currentHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
758
f7561f8d 759 // Matthias 20.05.2008
760 // here was a shadowed variable, sPrime is formerly defined
761 // renamed it to lsPrime ('local')
762 Double_t lsPrime = currentHit->GetS() - sav;
763 lsPrime += currentHit->GetZWeight();
764 ssPrime += currentHit->GetZWeight() * lsPrime;
765 sssPrime += currentHit->GetZWeight() * lsPrime * lsPrime;
e67b0680 766 szPrime += currentHit->GetZWeight() * currentHit->GetZ();
f7561f8d 767 sszPrime += currentHit->GetZWeight() * lsPrime * currentHit->GetZ();
db16520a 768 }
769
e67b0680 770 Double_t det = sPrime*sssPrime + ssPrime*ssPrime;
db16520a 771
772 if (fabs(det) < 1e-20) {
773 LOG(AliHLTTPCLog::kDebug,"AliHLTTPCConfMapFit::FitLineSZ","TrackFit") << "Determinant == 0" << ENDLOG;
774 chi2 = 99999.F ;
775 fTrack->SetChiSq2(chi2);
776 return -1 ;
777 }
778
e67b0680 779 Double_t b = (Double_t)(sPrime*sszPrime - ssPrime*szPrime) / det; // line parameter b
780 Double_t aPrime = (Double_t)(sssPrime*szPrime - ssPrime*sszPrime) / det; // line parameter a
db16520a 781
782 Double_t a = aPrime - b*sav;
783
e67b0680 784 Double_t sigma2b = (Double_t) 1. / sssPrime;
785 Double_t sigma2aprime = (Double_t) 1. /sPrime;
db16520a 786
787 Double_t sigma2a = sigma2aprime + sav*sav * sigma2b*sigma2b;
788
789 // Calculate chi2
790 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit()) {
791 AliHLTTPCConfMapPoint *currentHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
792 Double_t tempchi = currentHit->GetZ() - aPrime - b*(currentHit->GetS() - sav);
793 chi2 += tempchi*tempchi*currentHit->GetZWeight() ;
794 }
795
796 // Set TrackParameter
797 fTrack->SetChiSq2(chi2);
798 fTrack->SetTgl(b);
799 fTrack->SetZ0(a);
800 fTrack->SetTglerr(sigma2b);
801// fTrack->SetZ0err(sigma2aprime); // maybe subject to check
802 fTrack->SetZ0err(sigma2a); // maybe subject to check
803 return 0;
804}
805