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first steps to set the covariance matrix from the errors calculated in conformal...
[u/mrichter/AliRoot.git] / HLT / TPCLib / AliHLTTPCConfMapFit.cxx
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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
31f11c63 417 //set error for pT and Y. psi, Z and Tgl are set.
418
a6c02c85 419 //
420// Get errors from fast fit
421//
422 //if ( getPara()->getErrors ) getErrorsCircleFit ( acent, bcent, radius ) ;
423//
424 return 0 ;
425
426}
427
428//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
429// Fit Line in s-z plane
430//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
431Int_t AliHLTTPCConfMapFit::FitLine ( )
432{
433 //
434 //Initialization
435 //
436 Double_t sum = 0.F ;
437 Double_t ss = 0.F ;
438 Double_t sz = 0.F ;
439 Double_t sss = 0.F ;
440 Double_t ssz = 0.F ;
441 //
442 //find sum , sums ,sumz, sumss
443 //
444 Double_t dx, dy ;
445 Double_t radius = (Double_t)(fTrack->GetPt() / AliHLTTPCTransform::GetBFieldValue() ) ;
446
447 //TObjArray *hits = fTrack->GetHits();
e67b0680 448 //Int_t numOfHits = fTrack->GetNumberOfPoints();
a6c02c85 449
450 if (0)// fTrack->ComesFromMainVertex() == true )
451 {
452 dx = ((AliHLTTPCConfMapPoint*)fTrack->GetFirstHit())->GetX() - fVertex->GetX();
453 dy = ((AliHLTTPCConfMapPoint*)fTrack->GetFirstHit())->GetY() - fVertex->GetY() ;
454 }
455 else
456 {
457 dx = ((AliHLTTPCConfMapPoint *)fTrack->GetFirstHit())->GetX() - ((AliHLTTPCConfMapPoint *)fTrack->GetLastHit())->GetX() ;
458 dy = ((AliHLTTPCConfMapPoint *)fTrack->GetFirstHit())->GetY() - ((AliHLTTPCConfMapPoint *)fTrack->GetLastHit())->GetY() ;
459 //dx = ((AliHLTTPCConfMapPoint *)hits->First())->GetX() - ((AliHLTTPCConfMapPoint *)hits->Last())->GetX() ;
460 //dy = ((AliHLTTPCConfMapPoint *)hits->First())->GetY() - ((AliHLTTPCConfMapPoint *)hits->Last())->GetY() ;
461 }
462
463 Double_t localPsi = 0.5F * sqrt ( dx*dx + dy*dy ) / radius ;
e67b0680 464 Double_t totalS ;
a6c02c85 465
466 if ( fabs(localPsi) < 1. )
467 {
e67b0680 468 totalS = 2.0 * radius * asin ( localPsi ) ;
a6c02c85 469 }
470 else
471 {
e67b0680 472 totalS = 2.0 * radius * AliHLTTPCTransform::Pi() ;
a6c02c85 473 }
474
475 AliHLTTPCConfMapPoint *previousHit = NULL;
476
477 // FtfBaseHit *previousHit = 0 ;
478
479 //for ( startLoop() ; done() ; nextHit() ) {
480 Double_t dpsi,s;
481
e67b0680 482 // for(hit_counter=0; hit_counter<numOfHits; hit_counter++)
a6c02c85 483 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
484 {
485 // AliHLTTPCConfMapPoint *cHit = (AliHLTTPCConfMapPoint*)hits->At(hit_counter);
486 AliHLTTPCConfMapPoint *cHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
487 // if ( GetCurrentHit() != GetFirstHit() )
488 if(cHit != fTrack->GetFirstHit())// hits->First())
489 {
490 dx = cHit->GetX() - previousHit->GetX() ;
491 dy = cHit->GetY() - previousHit->GetY() ;
492 dpsi = 0.5 * (Double_t)sqrt ( dx*dx + dy*dy ) / radius ;
493 fTrack->SetPsierr(dpsi);
494 s = previousHit->GetS() - 2.0 * radius * (Double_t)asin ( dpsi ) ;
495 cHit->SetS(s);
496 }
497 else
e67b0680 498 cHit->SetS(totalS);
499 // cHit->s = totalS ;
a6c02c85 500
501 sum += cHit->GetZWeight() ;
502 ss += cHit->GetZWeight() * cHit->GetS() ;
503 sz += cHit->GetZWeight() * cHit->GetZ() ;
504 sss += cHit->GetZWeight() * cHit->GetS() * cHit->GetS() ;
505 ssz += cHit->GetZWeight() * cHit->GetS() * cHit->GetZ() ;
506 previousHit = cHit ;
507 }
508
509 Double_t chi2,det = sum * sss - ss * ss;
510 if ( fabs(det) < 1e-20)
511 {
512 chi2 = 99999.F ;
513 fTrack->SetChiSq2(chi2);
514 return 0 ;
515 }
516
517 //Compute the best fitted parameters A,B
518 Double_t tanl,z0,dtanl,dz0;
519
520 tanl = (Double_t)((sum * ssz - ss * sz ) / det );
521 z0 = (Double_t)((sz * sss - ssz * ss ) / det );
522
523 fTrack->SetTgl(tanl);
524 fTrack->SetZ0(z0);
525
526 // calculate chi-square
527
528 chi2 = 0.;
529 Double_t r1 ;
530
e67b0680 531 //for(hit_counter=0; hit_counter<numOfHits; hit_counter++)
a6c02c85 532 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
533 {
534 //AliHLTTPCConfMapPoint *cHit = (AliHLTTPCConfMapPoint*)hits->At(hit_counter);
535 AliHLTTPCConfMapPoint *cHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
536 r1 = cHit->GetZ() - tanl * cHit->GetS() - z0 ;
537 chi2 += (Double_t) ( (Double_t)cHit->GetZWeight() * (r1 * r1) );
538 }
539 fTrack->SetChiSq2(chi2);
540 //
541 // calculate estimated variance
542 // varsq=chi/(double(n)-2.)
543 // calculate covariance matrix
544 // siga=sqrt(varsq*sxx/det)
545 // sigb=sqrt(varsq*sum/det)
546 //
547 dtanl = (Double_t) ( sum / det );
548 dz0 = (Double_t) ( sss / det );
549
550 fTrack->SetTglerr(dtanl);
551 fTrack->SetZ0err(dz0);
552
553 return 0 ;
554}
db16520a 555
556
db16520a 557//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
558// Straight Line Fit in x-y plane
559//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
560Int_t AliHLTTPCConfMapFit::FitLineXY ( ){
561 // -----------------------------------------------------------------------------
562 // Implementation after Numerical Recipes in C, 2nd Edtion, chapter 15.2, p. 661
563 // with y = b*x + a
564 // and Data Analysis for Physical Science Students, Luis Lyons, chapter 2.4 p.51
565 // with y = a' + bx' , x' = x - <x>
566 // -----------------------------------------------------------------------------
567
e67b0680 568 Double_t s = 0.;
569 Double_t sx = 0.;
db16520a 570
e67b0680 571 Double_t sPrime = 0.;
572 Double_t sxPrime = 0.;
573 Double_t sxxPrime = 0.;
574 Double_t syPrime = 0.;
575 Double_t sxyPrime = 0.;
db16520a 576
577 Double_t chi2 = 0.;
578
e67b0680 579 Int_t numOfHits = fTrack->GetNumberOfPoints();
db16520a 580
581 Int_t co=0;
582
583 // - Loop over hits calculating average : xav
584 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit()) {
585 co++;
586 AliHLTTPCConfMapPoint *currentHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
587 // ** maybe not necessary, already done in ConfMapPoint
588 currentHit->SetXYWeight( 1./ (Double_t)(currentHit->GetXerr()*currentHit->GetXerr() + currentHit->GetYerr()*currentHit->GetYerr()) );
589 // **
e67b0680 590 s += currentHit->GetXYWeight();
591 sx += currentHit->GetXYWeight() * currentHit->GetX();
db16520a 592 }
593
e67b0680 594 if(co!=numOfHits)
595 LOG(AliHLTTPCLog::kError,"AliHLTTPCConfMapFit::FitLineXY","TrackFit") << "Mismatch of hits. Counter: "<<co<<" nHits: "<<numOfHits<<ENDLOG;
db16520a 596
e67b0680 597 Double_t xav = (Double_t)sx / s;
db16520a 598
599 // Calculate weighted means
600 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit()) {
601 AliHLTTPCConfMapPoint *currentHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
602
603 Double_t xPrime = currentHit->GetX() - xav;
e67b0680 604 sPrime += currentHit->GetXYWeight();
605 sxPrime += currentHit->GetXYWeight() * xPrime;
606 sxxPrime += currentHit->GetXYWeight() * xPrime * xPrime;
607 syPrime += currentHit->GetXYWeight() * currentHit->GetY();
608 sxyPrime += currentHit->GetXYWeight() * xPrime * currentHit->GetY();
db16520a 609 }
610
e67b0680 611 Double_t det = sPrime*sxxPrime + sxPrime*sxPrime;
db16520a 612
613 if (fabs(det) < 1e-20) {
614 LOG(AliHLTTPCLog::kDebug,"AliHLTTPCConfMapFit::FitLineXY","TrackFit") << "Determinant == 0" << ENDLOG;
615 chi2 = 99999.F ;
616 fTrack->SetChiSq1(chi2);
617 return -1 ;
618 }
619
e67b0680 620 Double_t b = (Double_t)(sPrime*sxyPrime - sxPrime*syPrime) / det; // line parameter b
621 Double_t aPrime = (Double_t)(sxxPrime*syPrime - sxPrime*sxyPrime) / det; // line parameter a
db16520a 622
e67b0680 623 Double_t sigma2b = (Double_t)1. / sxxPrime;
624 //-- Double_t sigma2aprime = (Double_t)1. /sPrime;
db16520a 625
626 // Get gradient angle psi of line in xy plane
627 Double_t psi = (Double_t) atan(b) ;
628
629 // Calculate chi2
630 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit()) {
631 AliHLTTPCConfMapPoint *currentHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
632 Double_t tempchi = currentHit->GetY() - aPrime - b*(currentHit->GetX() - xav);
633 chi2 += tempchi*tempchi*currentHit->GetXYWeight() ;
634 }
635
636 Double_t a = aPrime - b*xav;
637
638
639 // Set TrackParameter
640 fTrack->SetChiSq1(chi2);
641 fTrack->SetPsi(psi);
642 fTrack->SetPsierr(sigma2b);
643 fTrack->SetCenterX(0.); // Set to point on the track (for UpdateToFirstPoint)
644 fTrack->SetCenterY(a); // Set to point on the track (for UpdateToFirstPoint)
645
646 //Set the first point on the track to the space point coordinates of the innermost track
647 //This will be updated to lie on the fit later on (AliHLTTPCTrack::UpdateToFirstPoint).
648 AliHLTTPCConfMapPoint *lastHit = (AliHLTTPCConfMapPoint*)fTrack->GetLastHit();
649 Double_t x0 = lastHit->GetX();
650 Double_t y0 = lastHit->GetY();
651 fTrack->SetFirstPoint(x0,y0,0); //Z-value is set in FitLineSZ
652
653
654 //Set Defaults
655 fTrack->SetRadius(-1.);
656 fTrack->SetCharge(1);
657 fTrack->SetPt(-1.);
658
659
660 return 0;
661}
662
663
664//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
665// Straight Line Fit in s-z plane
666//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
667Int_t AliHLTTPCConfMapFit::FitLineSZ ( ){
668 // -----------------------------------------------------------------------------
669 // Implementation after Numerical Recipes in C, 2nd Edtion, chapter 15.2, p. 661
670 // with z = b*s + a
671 // and Data Analysis for Physical Science Students, Luis Lyons, chapter 2.4 p.51
672 // with z = a' + bs' , s' = s - <s>
673 // -----------------------------------------------------------------------------
674
675 Double_t S = 0.;
676 Double_t Ss = 0.;
677
e67b0680 678 Double_t sPrime = 0.;
679 Double_t ssPrime = 0.;
680 Double_t sssPrime = 0.;
681 Double_t szPrime = 0.;
682 Double_t sszPrime = 0.;
db16520a 683
684 Double_t chi2 = 0.;
e67b0680 685
686 // Matthias 16.10.2007
687 // what's that!!! local variables 's' and 'S'
688 // change Double_t s = 0.; -> slength
689 Double_t slength = 0.;
db16520a 690
691 AliHLTTPCConfMapPoint *previousHit = NULL;
692
693 // - Loop over hits calculating length in xy-plane: s
694 // - Loop over hits calculating average : sav
695 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit()) {
696 AliHLTTPCConfMapPoint *currentHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
697 if(currentHit != fTrack->GetFirstHit()) {
698 Double_t dx = currentHit->GetX() - previousHit->GetX() ;
699 Double_t dy = currentHit->GetY() - previousHit->GetY() ;
e67b0680 700 slength = previousHit->GetS() - (Double_t)sqrt ( dx*dx + dy*dy );
db16520a 701 }
702 else{
703 Double_t dx = ((AliHLTTPCConfMapPoint *)fTrack->GetFirstHit())->GetX() - ((AliHLTTPCConfMapPoint *)fTrack->GetLastHit())->GetX();
704 Double_t dy = ((AliHLTTPCConfMapPoint *)fTrack->GetFirstHit())->GetY() - ((AliHLTTPCConfMapPoint *)fTrack->GetLastHit())->GetY();
e67b0680 705 slength = (Double_t)sqrt ( dx*dx + dy*dy );
db16520a 706 }
707
e67b0680 708 currentHit->SetS(slength);
db16520a 709
710 S += currentHit->GetZWeight();
711 Ss += currentHit->GetZWeight() * currentHit->GetS();
712 }
713
714 Double_t sav = (Double_t)Ss / S;
715
716 // Calculate weighted means
717 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit()) {
718 AliHLTTPCConfMapPoint *currentHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
719
f7561f8d 720 // Matthias 20.05.2008
721 // here was a shadowed variable, sPrime is formerly defined
722 // renamed it to lsPrime ('local')
723 Double_t lsPrime = currentHit->GetS() - sav;
724 lsPrime += currentHit->GetZWeight();
725 ssPrime += currentHit->GetZWeight() * lsPrime;
726 sssPrime += currentHit->GetZWeight() * lsPrime * lsPrime;
e67b0680 727 szPrime += currentHit->GetZWeight() * currentHit->GetZ();
f7561f8d 728 sszPrime += currentHit->GetZWeight() * lsPrime * currentHit->GetZ();
db16520a 729 }
730
e67b0680 731 Double_t det = sPrime*sssPrime + ssPrime*ssPrime;
db16520a 732
733 if (fabs(det) < 1e-20) {
734 LOG(AliHLTTPCLog::kDebug,"AliHLTTPCConfMapFit::FitLineSZ","TrackFit") << "Determinant == 0" << ENDLOG;
735 chi2 = 99999.F ;
736 fTrack->SetChiSq2(chi2);
737 return -1 ;
738 }
739
e67b0680 740 Double_t b = (Double_t)(sPrime*sszPrime - ssPrime*szPrime) / det; // line parameter b
741 Double_t aPrime = (Double_t)(sssPrime*szPrime - ssPrime*sszPrime) / det; // line parameter a
db16520a 742
743 Double_t a = aPrime - b*sav;
744
e67b0680 745 Double_t sigma2b = (Double_t) 1. / sssPrime;
746 Double_t sigma2aprime = (Double_t) 1. /sPrime;
db16520a 747
748 Double_t sigma2a = sigma2aprime + sav*sav * sigma2b*sigma2b;
749
750 // Calculate chi2
751 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit()) {
752 AliHLTTPCConfMapPoint *currentHit = (AliHLTTPCConfMapPoint*)fTrack->GetCurrentHit();
753 Double_t tempchi = currentHit->GetZ() - aPrime - b*(currentHit->GetS() - sav);
754 chi2 += tempchi*tempchi*currentHit->GetZWeight() ;
755 }
756
757 // Set TrackParameter
758 fTrack->SetChiSq2(chi2);
759 fTrack->SetTgl(b);
760 fTrack->SetZ0(a);
761 fTrack->SetTglerr(sigma2b);
762// fTrack->SetZ0err(sigma2aprime); // maybe subject to check
763 fTrack->SetZ0err(sigma2a); // maybe subject to check
764 return 0;
765}
766