Added the magnetic field as a static member of the AliL3Transform class,
[u/mrichter/AliRoot.git] / HLT / src / AliL3ConfMapFit.cxx
CommitLineData
9392f4fd 1//$Id$
2
b661165c 3// Author: Anders Vestbo <mailto:vestbo@fi.uib.no>
4//*-- Copyright &copy ASV
5
108615fc 6#include <math.h>
7
9392f4fd 8#include "AliL3Defs.h"
108615fc 9#include "AliL3Logging.h"
10#include "AliL3ConfMapFit.h"
11#include "AliL3Vertex.h"
12#include "AliL3ConfMapTrack.h"
13#include "AliL3ConfMapPoint.h"
ef79795d 14#include "AliL3Transform.h"
108615fc 15
b661165c 16//_____________________________________________________________
108615fc 17// AliL3ConfMapFit
18//
19// Fit class for conformal mapping tracking
20
21ClassImp(AliL3ConfMapFit)
22
23Double_t AliL3ConfMapFit::pi=3.14159265358979323846;
24
25AliL3ConfMapFit::AliL3ConfMapFit(AliL3ConfMapTrack *track,AliL3Vertex *vertex)
26{
27 //constructor
28 fTrack = track;
29 fVertex = vertex;
30 BFACT = 0.0029980;
108615fc 31
32}
33
34Int_t AliL3ConfMapFit::FitHelix()
35{
36 if(FitCircle())
37 {
38 LOG(AliL3Log::kError,"AliL3ConfMapFit::FitHelix","TrackFit")<<AliL3Log::kDec<<
39 "Problems during circle fit"<<ENDLOG;
40 return 1;
41 }
42 if(FitLine())
43 {
44 LOG(AliL3Log::kError,"AliL3ConfMapFit::FitHelix","TrackFit")<<AliL3Log::kDec<<
45 "Problems during line fit"<<ENDLOG;
46 return 1;
47 }
48 return 0;
49}
50
51Int_t AliL3ConfMapFit::FitCircle()
52{
53 //-----------------------------------------------------------------
54 //Fits circle parameters using algorithm
55 //described by ChErnov and Oskov in Computer Physics
56 //Communications.
57 //
58 //Written in FORTRAN by Jawluen Tang, Physics department , UT-Austin
59 //Moved to C by Pablo Yepes
60 //Moved to AliROOT by ASV.
61 //------------------------------------------------------------------
62
63 Double_t wsum = 0.0 ;
64 Double_t xav = 0.0 ;
65 Double_t yav = 0.0 ;
66
67 Int_t num_of_hits = fTrack->GetNumberOfPoints();
68 //
69 // Loop over hits calculating average
70 Int_t co=0;
71
72 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
73 {
74 co++;
75 AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
76 cHit->SetXYWeight( 1./ (Double_t)(cHit->GetXerr()*cHit->GetXerr() + cHit->GetYerr()*cHit->GetYerr()) );
77 wsum += cHit->GetXYWeight() ;
78 xav += cHit->GetXYWeight() * cHit->GetX() ;
79 yav += cHit->GetXYWeight() * cHit->GetY() ;
80 }
81 if(co!=num_of_hits)
82 LOG(AliL3Log::kError,"AliL3ConfMapFit::FitCircle","TrackFit")<<AliL3Log::kDec<<
83 "Mismatch of hits. Counter: "<<co<<" nHits: "<<num_of_hits<<ENDLOG;
84 if (fTrack->ComesFromMainVertex() == true)
85 {
86 wsum += fVertex->GetXYWeight() ;
87 xav += fVertex->GetX() ;
88 yav += fVertex->GetY() ;
89 }
90
91 xav = xav / wsum ;
92 yav = yav / wsum ;
93//
94// CALCULATE <X**2>, <XY>, AND <Y**2> WITH <X> = 0, & <Y> = 0
95//
96 Double_t xxav = 0.0 ;
97 Double_t xyav = 0.0 ;
98 Double_t yyav = 0.0 ;
99 Double_t xi, yi ;
100
101 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
102 {
103 //AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint *)hits->At(hit_counter);
104 AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
105 xi = cHit->GetX() - xav ;
106 yi = cHit->GetY() - yav ;
107 xxav += xi * xi * cHit->GetXYWeight() ;
108 xyav += xi * yi * cHit->GetXYWeight() ;
109 yyav += yi * yi * cHit->GetXYWeight() ;
110 }
111
112 if (fTrack->ComesFromMainVertex() == true)
113 {
114 xi = fVertex->GetX() - xav ;
115 yi = fVertex->GetY() - yav ;
116 xxav += xi * xi * fVertex->GetXYWeight() ;
117 xyav += xi * yi * fVertex->GetXYWeight() ;
118 yyav += yi * yi * fVertex->GetXYWeight() ;
119 }
120 xxav = xxav / wsum ;
121 xyav = xyav / wsum ;
122 yyav = yyav / wsum ;
123//
124//--> ROTATE COORDINATES SO THAT <XY> = 0
125//
126//--> SIGN(C**2 - S**2) = SIGN(XXAV - YYAV) >
127//--> & > ==> NEW : (XXAV-YYAV) > 0
128//--> SIGN(S) = SIGN(XYAV) >
129
130 Double_t a = fabs( xxav - yyav ) ;
131 Double_t b = 4.0 * xyav * xyav ;
132
133 Double_t asqpb = a * a + b ;
134 Double_t rasqpb = sqrt ( asqpb) ;
135
136 Double_t splus = 1.0 + a / rasqpb ;
137 Double_t sminus = b / (asqpb * splus) ;
138
139 splus = sqrt (0.5 * splus ) ;
140 sminus = sqrt (0.5 * sminus) ;
141//
142//-> FIRST REQUIRE : SIGN(C**2 - S**2) = SIGN(XXAV - YYAV)
143//
144 Double_t sinrot, cosrot ;
145 if ( xxav <= yyav ) {
146 cosrot = sminus ;
147 sinrot = splus ;
148 }
149 else {
150 cosrot = splus ;
151 sinrot = sminus ;
152 }
153//
154//-> REQUIRE : SIGN(S) = SIGN(XYAV) * SIGN(C) (ASSUMING SIGN(C) > 0)
155//
156 if ( xyav < 0.0 ) sinrot = - sinrot ;
157//
158//--> WE NOW HAVE THE SMALLEST ANGLE THAT GUARANTEES <X**2> > <Y**2>
159//--> TO GET THE SIGN OF THE CHARGE RIGHT, THE NEW X-AXIS MUST POINT
160//--> OUTWARD FROM THE ORGIN. WE ARE FREE TO CHANGE SIGNS OF BOTH
161//--> COSROT AND SINROT SIMULTANEOUSLY TO ACCOMPLISH THIS.
162//
163//--> CHOOSE SIGN OF C WISELY TO BE ABLE TO GET THE SIGN OF THE CHARGE
164//
165 if ( cosrot*xav+sinrot*yav < 0.0 ) {
166 cosrot = -cosrot ;
167 sinrot = -sinrot ;
168 }
169//
170//-> NOW GET <R**2> AND RSCALE= SQRT(<R**2>)
171//
172 Double_t rrav = xxav + yyav ;
173 Double_t rscale = sqrt(rrav) ;
174
175 xxav = 0.0 ;
176 yyav = 0.0 ;
177 xyav = 0.0 ;
178 Double_t xrrav = 0.0 ;
179 Double_t yrrav = 0.0 ;
180 Double_t rrrrav = 0.0 ;
181
182 Double_t xixi, yiyi, riri, wiriri, xold, yold ;
183
184 //for (hit_counter=0; hit_counter<num_of_hits; hit_counter++)
185 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
186 {
187 //AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)hits->At(hit_counter);
188 AliL3ConfMapPoint* cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
189
190 xold = cHit->GetX() - xav ;
191 yold = cHit->GetY() - yav ;
192 //
193 //--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
194 //
195 xi = ( cosrot * xold + sinrot * yold ) / rscale ;
196 yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
197
198 xixi = xi * xi ;
199 yiyi = yi * yi ;
200 riri = xixi + yiyi ;
201 wiriri = cHit->GetXYWeight() * riri ;
202
203 xyav += cHit->GetXYWeight() * xi * yi ;
204 xxav += cHit->GetXYWeight() * xixi ;
205 yyav += cHit->GetXYWeight() * yiyi ;
206
207 xrrav += wiriri * xi ;
208 yrrav += wiriri * yi ;
209 rrrrav += wiriri * riri ;
210 }
211 //
212// Include vertex if required
213//
214 if (fTrack->ComesFromMainVertex() == true)
215 {
216 xold = fVertex->GetX() - xav ;
217 yold = fVertex->GetY() - yav ;
218 //
219 //--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
220 //
221 xi = ( cosrot * xold + sinrot * yold ) / rscale ;
222 yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
223
224 xixi = xi * xi ;
225 yiyi = yi * yi ;
226 riri = xixi + yiyi ;
227 wiriri = fVertex->GetXYWeight() * riri ;
228
229 xyav += fVertex->GetXYWeight() * xi * yi ;
230 xxav += fVertex->GetXYWeight() * xixi ;
231 yyav += fVertex->GetXYWeight() * yiyi ;
232
233 xrrav += wiriri * xi ;
234 yrrav += wiriri * yi ;
235 rrrrav += wiriri * riri ;
236 }
237 //
238 //
239 //
240 //--> DIVIDE BY WSUM TO MAKE AVERAGES
241 //
242 xxav = xxav / wsum ;
243 yyav = yyav / wsum ;
244 xrrav = xrrav / wsum ;
245 yrrav = yrrav / wsum ;
246 rrrrav = rrrrav / wsum ;
247 xyav = xyav / wsum ;
248
249 Int_t const ntry = 5 ;
250//
251//--> USE THESE TO GET THE COEFFICIENTS OF THE 4-TH ORDER POLYNIMIAL
252//--> DON'T PANIC - THE THIRD ORDER TERM IS ZERO !
253//
254 Double_t xrrxrr = xrrav * xrrav ;
255 Double_t yrryrr = yrrav * yrrav ;
256 Double_t rrrrm1 = rrrrav - 1.0 ;
257 Double_t xxyy = xxav * yyav ;
258
259 Double_t c0 = rrrrm1*xxyy - xrrxrr*yyav - yrryrr*xxav ;
260 Double_t c1 = - rrrrm1 + xrrxrr + yrryrr - 4.0*xxyy ;
261 Double_t c2 = 4.0 + rrrrm1 - 4.0*xxyy ;
262 Double_t c4 = - 4.0 ;
263//
264//--> COEFFICIENTS OF THE DERIVATIVE - USED IN NEWTON-RAPHSON ITERATIONS
265//
266 Double_t c2d = 2.0 * c2 ;
267 Double_t c4d = 4.0 * c4 ;
268//
269//--> 0'TH VALUE OF LAMDA - LINEAR INTERPOLATION BETWEEN P(0) & P(YYAV)
270//
271// LAMDA = YYAV * C0 / (C0 + YRRSQ * (XXAV-YYAV))
272 Double_t lamda = 0.0 ;
273 Double_t dlamda = 0.0 ;
274//
275 Double_t chiscl = wsum * rscale * rscale ;
276 Double_t dlamax = 0.001 / chiscl ;
277
278 Double_t p, pd ;
279 for ( int itry = 1 ; itry <= ntry ; itry++ ) {
280 p = c0 + lamda * (c1 + lamda * (c2 + lamda * lamda * c4 )) ;
281 pd = (c1 + lamda * (c2d + lamda * lamda * c4d)) ;
282 dlamda = -p / pd ;
283 lamda = lamda + dlamda ;
284 if (fabs(dlamda)< dlamax) break ;
285 }
286
287 Double_t chi2 = (Double_t)(chiscl * lamda) ;
288
289 fTrack->SetChiSq1(chi2);
290 // Double_t dchisq = chiscl * dlamda ;
291//
292//--> NOW CALCULATE THE MATRIX ELEMENTS FOR ALPHA, BETA & KAPPA
293//
294 Double_t h11 = xxav - lamda ;
295 Double_t h14 = xrrav ;
296 Double_t h22 = yyav - lamda ;
297 Double_t h24 = yrrav ;
298 Double_t h34 = 1.0 + 2.0*lamda ;
299 if ( h11 == 0.0 || h22 == 0.0 ){
300 LOG(AliL3Log::kError,"AliL3ConfMapFit::FitCircle","TrackFit")<<AliL3Log::kDec<<
301 "Problems fitting circle"<<ENDLOG;
302 return 1 ;
303 }
304 Double_t rootsq = (h14*h14)/(h11*h11) + 4.0*h34 ;
305
306 Double_t ratio, kappa, beta ;
307 if ( fabs(h22) > fabs(h24) ) {
308 ratio = h24 / h22 ;
309 rootsq = ratio * ratio + rootsq ;
310 kappa = 1.0 / sqrt(rootsq) ;
311 beta = - ratio * kappa ;
312 }
313 else {
314 ratio = h22 / h24 ;
315 rootsq = 1.0 + ratio * ratio * rootsq ;
316 beta = 1.0 / sqrt(rootsq) ;
317 if ( h24 > 0 ) beta = - beta ;
318 kappa = -ratio * beta ;
319 }
320 Double_t alpha = - (h14/h11) * kappa ;
321//
322//--> transform these into the lab coordinate system
323//--> first get kappa and back to real dimensions
324//
325 Double_t kappa1 = kappa / rscale ;
326 Double_t dbro = 0.5 / kappa1 ;
327//
328//--> next rotate alpha and beta and scale
329//
330 Double_t alphar = (cosrot * alpha - sinrot * beta)* dbro ;
331 Double_t betar = (sinrot * alpha + cosrot * beta)* dbro ;
332//
333//--> then translate by (xav,yav)
334//
335 Double_t acent = (double)(xav - alphar) ;
336 Double_t bcent = (double)(yav - betar ) ;
337 Double_t radius = (double)dbro ;
338//
339// Get charge
340//
5dd30052 341 Int_t q = ( ( yrrav < 0 ) ? 1 : -1 ) ;
108615fc 342
343 fTrack->SetCharge(q);
344
345//
346// Get other track parameters
347//
348 Double_t x0, y0,phi0,r0,psi,pt ;
349 if ( fTrack->ComesFromMainVertex() == true )
350 {
351 //flag = 1 ; // primary track flag
352 x0 = fVertex->GetX() ;
353 y0 = fVertex->GetY() ;
354 phi0 = fVertex->GetPhi() ;
355 r0 = fVertex->GetR() ;
356 fTrack->SetPhi0(phi0);
357 fTrack->SetR0(r0);
358 }
359 else
360 {
361 //AliL3ConfMapPoint *lHit = (AliL3ConfMapPoint*)hits->Last();
362 AliL3ConfMapPoint *lHit = (AliL3ConfMapPoint*)fTrack->lastHit;
363 //flag = 0 ; // primary track flag
364 x0 = lHit->GetX() ;
365 y0 = lHit->GetY() ;
366 phi0 = atan2(lHit->GetY(),lHit->GetX());
367 if ( phi0 < 0 ) phi0 += 2*pi;
368 r0 = sqrt ( lHit->GetX() * lHit->GetX() + lHit->GetY() * lHit->GetY() ) ;
369 fTrack->SetPhi0(phi0);
370 fTrack->SetR0(r0);
371 }
372 //
373 psi = (Double_t)atan2(bcent-y0,acent-x0) ;
374 psi = psi + q * 0.5F * pi ;
375 if ( psi < 0 ) psi = psi + 2*pi;
376
ef79795d 377 pt = (Double_t)(BFACT * AliL3Transform::GetBField() * radius ) ;
108615fc 378 fTrack->SetPsi(psi);
379 fTrack->SetPt(pt);
380
381 //
382// Get errors from fast fit
383//
384 //if ( getPara()->getErrors ) getErrorsCircleFit ( acent, bcent, radius ) ;
385//
386 return 0 ;
387
388}
389
390//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
391// Fit Line in s-z plane
392//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
393Int_t AliL3ConfMapFit::FitLine ( )
394{
395 //
396 //Initialization
397 //
398 Double_t sum = 0.F ;
399 Double_t ss = 0.F ;
400 Double_t sz = 0.F ;
401 Double_t sss = 0.F ;
402 Double_t ssz = 0.F ;
403 //
404 //find sum , sums ,sumz, sumss
405 //
406 Double_t dx, dy ;
ef79795d 407 Double_t radius = (Double_t)(fTrack->GetPt() / ( BFACT * AliL3Transform::GetBField() ) ) ;
108615fc 408
409 //TObjArray *hits = fTrack->GetHits();
410 //Int_t num_of_hits = fTrack->GetNumberOfPoints();
411
412 if ( fTrack->ComesFromMainVertex() == true )
413 {
414 dx = ((AliL3ConfMapPoint*)fTrack->firstHit)->GetX() - fVertex->GetX();
415 dy = ((AliL3ConfMapPoint*)fTrack->firstHit)->GetY() - fVertex->GetY() ;
416 }
417 else
418 {
419 dx = ((AliL3ConfMapPoint *)fTrack->firstHit)->GetX() - ((AliL3ConfMapPoint *)fTrack->lastHit)->GetX() ;
420 dy = ((AliL3ConfMapPoint *)fTrack->firstHit)->GetY() - ((AliL3ConfMapPoint *)fTrack->lastHit)->GetY() ;
421 //dx = ((AliL3ConfMapPoint *)hits->First())->GetX() - ((AliL3ConfMapPoint *)hits->Last())->GetX() ;
422 //dy = ((AliL3ConfMapPoint *)hits->First())->GetY() - ((AliL3ConfMapPoint *)hits->Last())->GetY() ;
423 }
424
425 Double_t localPsi = 0.5F * sqrt ( dx*dx + dy*dy ) / radius ;
426 Double_t total_s ;
427
428 if ( fabs(localPsi) < 1. )
429 {
430 total_s = 2.0 * radius * asin ( localPsi ) ;
431 }
432 else
433 {
434 total_s = 2.0 * radius * pi ;
435 }
436
437 AliL3ConfMapPoint *previousHit = NULL;
438
439 // FtfBaseHit *previousHit = 0 ;
440
441 //for ( startLoop() ; done() ; nextHit() ) {
442 Double_t dpsi,s;
443
444 // for(hit_counter=0; hit_counter<num_of_hits; hit_counter++)
445 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
446 {
447 // AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)hits->At(hit_counter);
448 AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
449 // if ( currentHit != firstHit )
450 if(cHit != fTrack->firstHit)// hits->First())
451 {
452 dx = cHit->GetX() - previousHit->GetX() ;
453 dy = cHit->GetY() - previousHit->GetY() ;
454 dpsi = 0.5 * (Double_t)sqrt ( dx*dx + dy*dy ) / radius ;
455 fTrack->SetPsierr(dpsi);
456 s = previousHit->GetS() - 2.0 * radius * (Double_t)asin ( dpsi ) ;
457 cHit->SetS(s);
458 }
459 else
460 cHit->SetS(total_s);
461 // cHit->s = total_s ;
462
463 sum += cHit->GetZWeight() ;
464 ss += cHit->GetZWeight() * cHit->GetS() ;
465 sz += cHit->GetZWeight() * cHit->GetZ() ;
466 sss += cHit->GetZWeight() * cHit->GetS() * cHit->GetS() ;
467 ssz += cHit->GetZWeight() * cHit->GetS() * cHit->GetZ() ;
468 previousHit = cHit ;
469 }
470
471 Double_t chi2,det = sum * sss - ss * ss;
472 if ( fabs(det) < 1e-20)
473 {
474 chi2 = 99999.F ;
475 fTrack->SetChiSq2(chi2);
476 return 0 ;
477 }
478
479 //Compute the best fitted parameters A,B
480 Double_t tanl,z0,dtanl,dz0;
481
482 tanl = (Double_t)((sum * ssz - ss * sz ) / det );
483 z0 = (Double_t)((sz * sss - ssz * ss ) / det );
484
485 fTrack->SetTgl(tanl);
486 fTrack->SetZ0(z0);
487
488 // calculate chi-square
489
490 chi2 = 0.;
491 Double_t r1 ;
492
493 //for(hit_counter=0; hit_counter<num_of_hits; hit_counter++)
494 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
495 {
496 //AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)hits->At(hit_counter);
497 AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
498 r1 = cHit->GetZ() - tanl * cHit->GetS() - z0 ;
499 chi2 += (Double_t) ( (Double_t)cHit->GetZWeight() * (r1 * r1) );
500 }
501 fTrack->SetChiSq2(chi2);
502 //
503 // calculate estimated variance
504 // varsq=chi/(double(n)-2.)
505 // calculate covariance matrix
506 // siga=sqrt(varsq*sxx/det)
507 // sigb=sqrt(varsq*sum/det)
508 //
509 dtanl = (Double_t) ( sum / det );
510 dz0 = (Double_t) ( sss / det );
511
512 fTrack->SetTglerr(dtanl);
513 fTrack->SetZ0err(dz0);
514
515 return 0 ;
516}