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[u/mrichter/AliRoot.git] / HLT / src / AliL3ConfMapFit.cxx
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108615fc 1#include <math.h>
2
3#include "AliL3Logging.h"
4#include "AliL3ConfMapFit.h"
5#include "AliL3Vertex.h"
6#include "AliL3ConfMapTrack.h"
7#include "AliL3ConfMapPoint.h"
8
9//_______________________________
10// AliL3ConfMapFit
11//
12// Fit class for conformal mapping tracking
13
14ClassImp(AliL3ConfMapFit)
15
16Double_t AliL3ConfMapFit::pi=3.14159265358979323846;
17
18AliL3ConfMapFit::AliL3ConfMapFit(AliL3ConfMapTrack *track,AliL3Vertex *vertex)
19{
20 //constructor
21 fTrack = track;
22 fVertex = vertex;
23 BFACT = 0.0029980;
24 bField = 0.2;
25
26}
27
28Int_t AliL3ConfMapFit::FitHelix()
29{
30 if(FitCircle())
31 {
32 LOG(AliL3Log::kError,"AliL3ConfMapFit::FitHelix","TrackFit")<<AliL3Log::kDec<<
33 "Problems during circle fit"<<ENDLOG;
34 return 1;
35 }
36 if(FitLine())
37 {
38 LOG(AliL3Log::kError,"AliL3ConfMapFit::FitHelix","TrackFit")<<AliL3Log::kDec<<
39 "Problems during line fit"<<ENDLOG;
40 return 1;
41 }
42 return 0;
43}
44
45Int_t AliL3ConfMapFit::FitCircle()
46{
47 //-----------------------------------------------------------------
48 //Fits circle parameters using algorithm
49 //described by ChErnov and Oskov in Computer Physics
50 //Communications.
51 //
52 //Written in FORTRAN by Jawluen Tang, Physics department , UT-Austin
53 //Moved to C by Pablo Yepes
54 //Moved to AliROOT by ASV.
55 //------------------------------------------------------------------
56
57 Double_t wsum = 0.0 ;
58 Double_t xav = 0.0 ;
59 Double_t yav = 0.0 ;
60
61 Int_t num_of_hits = fTrack->GetNumberOfPoints();
62 //
63 // Loop over hits calculating average
64 Int_t co=0;
65
66 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
67 {
68 co++;
69 AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
70 cHit->SetXYWeight( 1./ (Double_t)(cHit->GetXerr()*cHit->GetXerr() + cHit->GetYerr()*cHit->GetYerr()) );
71 wsum += cHit->GetXYWeight() ;
72 xav += cHit->GetXYWeight() * cHit->GetX() ;
73 yav += cHit->GetXYWeight() * cHit->GetY() ;
74 }
75 if(co!=num_of_hits)
76 LOG(AliL3Log::kError,"AliL3ConfMapFit::FitCircle","TrackFit")<<AliL3Log::kDec<<
77 "Mismatch of hits. Counter: "<<co<<" nHits: "<<num_of_hits<<ENDLOG;
78 if (fTrack->ComesFromMainVertex() == true)
79 {
80 wsum += fVertex->GetXYWeight() ;
81 xav += fVertex->GetX() ;
82 yav += fVertex->GetY() ;
83 }
84
85 xav = xav / wsum ;
86 yav = yav / wsum ;
87//
88// CALCULATE <X**2>, <XY>, AND <Y**2> WITH <X> = 0, & <Y> = 0
89//
90 Double_t xxav = 0.0 ;
91 Double_t xyav = 0.0 ;
92 Double_t yyav = 0.0 ;
93 Double_t xi, yi ;
94
95 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
96 {
97 //AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint *)hits->At(hit_counter);
98 AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
99 xi = cHit->GetX() - xav ;
100 yi = cHit->GetY() - yav ;
101 xxav += xi * xi * cHit->GetXYWeight() ;
102 xyav += xi * yi * cHit->GetXYWeight() ;
103 yyav += yi * yi * cHit->GetXYWeight() ;
104 }
105
106 if (fTrack->ComesFromMainVertex() == true)
107 {
108 xi = fVertex->GetX() - xav ;
109 yi = fVertex->GetY() - yav ;
110 xxav += xi * xi * fVertex->GetXYWeight() ;
111 xyav += xi * yi * fVertex->GetXYWeight() ;
112 yyav += yi * yi * fVertex->GetXYWeight() ;
113 }
114 xxav = xxav / wsum ;
115 xyav = xyav / wsum ;
116 yyav = yyav / wsum ;
117//
118//--> ROTATE COORDINATES SO THAT <XY> = 0
119//
120//--> SIGN(C**2 - S**2) = SIGN(XXAV - YYAV) >
121//--> & > ==> NEW : (XXAV-YYAV) > 0
122//--> SIGN(S) = SIGN(XYAV) >
123
124 Double_t a = fabs( xxav - yyav ) ;
125 Double_t b = 4.0 * xyav * xyav ;
126
127 Double_t asqpb = a * a + b ;
128 Double_t rasqpb = sqrt ( asqpb) ;
129
130 Double_t splus = 1.0 + a / rasqpb ;
131 Double_t sminus = b / (asqpb * splus) ;
132
133 splus = sqrt (0.5 * splus ) ;
134 sminus = sqrt (0.5 * sminus) ;
135//
136//-> FIRST REQUIRE : SIGN(C**2 - S**2) = SIGN(XXAV - YYAV)
137//
138 Double_t sinrot, cosrot ;
139 if ( xxav <= yyav ) {
140 cosrot = sminus ;
141 sinrot = splus ;
142 }
143 else {
144 cosrot = splus ;
145 sinrot = sminus ;
146 }
147//
148//-> REQUIRE : SIGN(S) = SIGN(XYAV) * SIGN(C) (ASSUMING SIGN(C) > 0)
149//
150 if ( xyav < 0.0 ) sinrot = - sinrot ;
151//
152//--> WE NOW HAVE THE SMALLEST ANGLE THAT GUARANTEES <X**2> > <Y**2>
153//--> TO GET THE SIGN OF THE CHARGE RIGHT, THE NEW X-AXIS MUST POINT
154//--> OUTWARD FROM THE ORGIN. WE ARE FREE TO CHANGE SIGNS OF BOTH
155//--> COSROT AND SINROT SIMULTANEOUSLY TO ACCOMPLISH THIS.
156//
157//--> CHOOSE SIGN OF C WISELY TO BE ABLE TO GET THE SIGN OF THE CHARGE
158//
159 if ( cosrot*xav+sinrot*yav < 0.0 ) {
160 cosrot = -cosrot ;
161 sinrot = -sinrot ;
162 }
163//
164//-> NOW GET <R**2> AND RSCALE= SQRT(<R**2>)
165//
166 Double_t rrav = xxav + yyav ;
167 Double_t rscale = sqrt(rrav) ;
168
169 xxav = 0.0 ;
170 yyav = 0.0 ;
171 xyav = 0.0 ;
172 Double_t xrrav = 0.0 ;
173 Double_t yrrav = 0.0 ;
174 Double_t rrrrav = 0.0 ;
175
176 Double_t xixi, yiyi, riri, wiriri, xold, yold ;
177
178 //for (hit_counter=0; hit_counter<num_of_hits; hit_counter++)
179 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
180 {
181 //AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)hits->At(hit_counter);
182 AliL3ConfMapPoint* cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
183
184 xold = cHit->GetX() - xav ;
185 yold = cHit->GetY() - yav ;
186 //
187 //--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
188 //
189 xi = ( cosrot * xold + sinrot * yold ) / rscale ;
190 yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
191
192 xixi = xi * xi ;
193 yiyi = yi * yi ;
194 riri = xixi + yiyi ;
195 wiriri = cHit->GetXYWeight() * riri ;
196
197 xyav += cHit->GetXYWeight() * xi * yi ;
198 xxav += cHit->GetXYWeight() * xixi ;
199 yyav += cHit->GetXYWeight() * yiyi ;
200
201 xrrav += wiriri * xi ;
202 yrrav += wiriri * yi ;
203 rrrrav += wiriri * riri ;
204 }
205 //
206// Include vertex if required
207//
208 if (fTrack->ComesFromMainVertex() == true)
209 {
210 xold = fVertex->GetX() - xav ;
211 yold = fVertex->GetY() - yav ;
212 //
213 //--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
214 //
215 xi = ( cosrot * xold + sinrot * yold ) / rscale ;
216 yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
217
218 xixi = xi * xi ;
219 yiyi = yi * yi ;
220 riri = xixi + yiyi ;
221 wiriri = fVertex->GetXYWeight() * riri ;
222
223 xyav += fVertex->GetXYWeight() * xi * yi ;
224 xxav += fVertex->GetXYWeight() * xixi ;
225 yyav += fVertex->GetXYWeight() * yiyi ;
226
227 xrrav += wiriri * xi ;
228 yrrav += wiriri * yi ;
229 rrrrav += wiriri * riri ;
230 }
231 //
232 //
233 //
234 //--> DIVIDE BY WSUM TO MAKE AVERAGES
235 //
236 xxav = xxav / wsum ;
237 yyav = yyav / wsum ;
238 xrrav = xrrav / wsum ;
239 yrrav = yrrav / wsum ;
240 rrrrav = rrrrav / wsum ;
241 xyav = xyav / wsum ;
242
243 Int_t const ntry = 5 ;
244//
245//--> USE THESE TO GET THE COEFFICIENTS OF THE 4-TH ORDER POLYNIMIAL
246//--> DON'T PANIC - THE THIRD ORDER TERM IS ZERO !
247//
248 Double_t xrrxrr = xrrav * xrrav ;
249 Double_t yrryrr = yrrav * yrrav ;
250 Double_t rrrrm1 = rrrrav - 1.0 ;
251 Double_t xxyy = xxav * yyav ;
252
253 Double_t c0 = rrrrm1*xxyy - xrrxrr*yyav - yrryrr*xxav ;
254 Double_t c1 = - rrrrm1 + xrrxrr + yrryrr - 4.0*xxyy ;
255 Double_t c2 = 4.0 + rrrrm1 - 4.0*xxyy ;
256 Double_t c4 = - 4.0 ;
257//
258//--> COEFFICIENTS OF THE DERIVATIVE - USED IN NEWTON-RAPHSON ITERATIONS
259//
260 Double_t c2d = 2.0 * c2 ;
261 Double_t c4d = 4.0 * c4 ;
262//
263//--> 0'TH VALUE OF LAMDA - LINEAR INTERPOLATION BETWEEN P(0) & P(YYAV)
264//
265// LAMDA = YYAV * C0 / (C0 + YRRSQ * (XXAV-YYAV))
266 Double_t lamda = 0.0 ;
267 Double_t dlamda = 0.0 ;
268//
269 Double_t chiscl = wsum * rscale * rscale ;
270 Double_t dlamax = 0.001 / chiscl ;
271
272 Double_t p, pd ;
273 for ( int itry = 1 ; itry <= ntry ; itry++ ) {
274 p = c0 + lamda * (c1 + lamda * (c2 + lamda * lamda * c4 )) ;
275 pd = (c1 + lamda * (c2d + lamda * lamda * c4d)) ;
276 dlamda = -p / pd ;
277 lamda = lamda + dlamda ;
278 if (fabs(dlamda)< dlamax) break ;
279 }
280
281 Double_t chi2 = (Double_t)(chiscl * lamda) ;
282
283 fTrack->SetChiSq1(chi2);
284 // Double_t dchisq = chiscl * dlamda ;
285//
286//--> NOW CALCULATE THE MATRIX ELEMENTS FOR ALPHA, BETA & KAPPA
287//
288 Double_t h11 = xxav - lamda ;
289 Double_t h14 = xrrav ;
290 Double_t h22 = yyav - lamda ;
291 Double_t h24 = yrrav ;
292 Double_t h34 = 1.0 + 2.0*lamda ;
293 if ( h11 == 0.0 || h22 == 0.0 ){
294 LOG(AliL3Log::kError,"AliL3ConfMapFit::FitCircle","TrackFit")<<AliL3Log::kDec<<
295 "Problems fitting circle"<<ENDLOG;
296 return 1 ;
297 }
298 Double_t rootsq = (h14*h14)/(h11*h11) + 4.0*h34 ;
299
300 Double_t ratio, kappa, beta ;
301 if ( fabs(h22) > fabs(h24) ) {
302 ratio = h24 / h22 ;
303 rootsq = ratio * ratio + rootsq ;
304 kappa = 1.0 / sqrt(rootsq) ;
305 beta = - ratio * kappa ;
306 }
307 else {
308 ratio = h22 / h24 ;
309 rootsq = 1.0 + ratio * ratio * rootsq ;
310 beta = 1.0 / sqrt(rootsq) ;
311 if ( h24 > 0 ) beta = - beta ;
312 kappa = -ratio * beta ;
313 }
314 Double_t alpha = - (h14/h11) * kappa ;
315//
316//--> transform these into the lab coordinate system
317//--> first get kappa and back to real dimensions
318//
319 Double_t kappa1 = kappa / rscale ;
320 Double_t dbro = 0.5 / kappa1 ;
321//
322//--> next rotate alpha and beta and scale
323//
324 Double_t alphar = (cosrot * alpha - sinrot * beta)* dbro ;
325 Double_t betar = (sinrot * alpha + cosrot * beta)* dbro ;
326//
327//--> then translate by (xav,yav)
328//
329 Double_t acent = (double)(xav - alphar) ;
330 Double_t bcent = (double)(yav - betar ) ;
331 Double_t radius = (double)dbro ;
332//
333// Get charge
334//
335 Double_t q = ( ( yrrav < 0 ) ? 1 : -1 ) ;
336
337 fTrack->SetCharge(q);
338
339//
340// Get other track parameters
341//
342 Double_t x0, y0,phi0,r0,psi,pt ;
343 if ( fTrack->ComesFromMainVertex() == true )
344 {
345 //flag = 1 ; // primary track flag
346 x0 = fVertex->GetX() ;
347 y0 = fVertex->GetY() ;
348 phi0 = fVertex->GetPhi() ;
349 r0 = fVertex->GetR() ;
350 fTrack->SetPhi0(phi0);
351 fTrack->SetR0(r0);
352 }
353 else
354 {
355 //AliL3ConfMapPoint *lHit = (AliL3ConfMapPoint*)hits->Last();
356 AliL3ConfMapPoint *lHit = (AliL3ConfMapPoint*)fTrack->lastHit;
357 //flag = 0 ; // primary track flag
358 x0 = lHit->GetX() ;
359 y0 = lHit->GetY() ;
360 phi0 = atan2(lHit->GetY(),lHit->GetX());
361 if ( phi0 < 0 ) phi0 += 2*pi;
362 r0 = sqrt ( lHit->GetX() * lHit->GetX() + lHit->GetY() * lHit->GetY() ) ;
363 fTrack->SetPhi0(phi0);
364 fTrack->SetR0(r0);
365 }
366 //
367 psi = (Double_t)atan2(bcent-y0,acent-x0) ;
368 psi = psi + q * 0.5F * pi ;
369 if ( psi < 0 ) psi = psi + 2*pi;
370
371 pt = (Double_t)(BFACT * bField * radius ) ;
372 fTrack->SetPsi(psi);
373 fTrack->SetPt(pt);
374
375 //
376// Get errors from fast fit
377//
378 //if ( getPara()->getErrors ) getErrorsCircleFit ( acent, bcent, radius ) ;
379//
380 return 0 ;
381
382}
383
384//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
385// Fit Line in s-z plane
386//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
387Int_t AliL3ConfMapFit::FitLine ( )
388{
389 //
390 //Initialization
391 //
392 Double_t sum = 0.F ;
393 Double_t ss = 0.F ;
394 Double_t sz = 0.F ;
395 Double_t sss = 0.F ;
396 Double_t ssz = 0.F ;
397 //
398 //find sum , sums ,sumz, sumss
399 //
400 Double_t dx, dy ;
401 Double_t radius = (Double_t)(fTrack->GetPt() / ( BFACT * bField ) ) ;
402
403 //TObjArray *hits = fTrack->GetHits();
404 //Int_t num_of_hits = fTrack->GetNumberOfPoints();
405
406 if ( fTrack->ComesFromMainVertex() == true )
407 {
408 dx = ((AliL3ConfMapPoint*)fTrack->firstHit)->GetX() - fVertex->GetX();
409 dy = ((AliL3ConfMapPoint*)fTrack->firstHit)->GetY() - fVertex->GetY() ;
410 }
411 else
412 {
413 dx = ((AliL3ConfMapPoint *)fTrack->firstHit)->GetX() - ((AliL3ConfMapPoint *)fTrack->lastHit)->GetX() ;
414 dy = ((AliL3ConfMapPoint *)fTrack->firstHit)->GetY() - ((AliL3ConfMapPoint *)fTrack->lastHit)->GetY() ;
415 //dx = ((AliL3ConfMapPoint *)hits->First())->GetX() - ((AliL3ConfMapPoint *)hits->Last())->GetX() ;
416 //dy = ((AliL3ConfMapPoint *)hits->First())->GetY() - ((AliL3ConfMapPoint *)hits->Last())->GetY() ;
417 }
418
419 Double_t localPsi = 0.5F * sqrt ( dx*dx + dy*dy ) / radius ;
420 Double_t total_s ;
421
422 if ( fabs(localPsi) < 1. )
423 {
424 total_s = 2.0 * radius * asin ( localPsi ) ;
425 }
426 else
427 {
428 total_s = 2.0 * radius * pi ;
429 }
430
431 AliL3ConfMapPoint *previousHit = NULL;
432
433 // FtfBaseHit *previousHit = 0 ;
434
435 //for ( startLoop() ; done() ; nextHit() ) {
436 Double_t dpsi,s;
437
438 // for(hit_counter=0; hit_counter<num_of_hits; hit_counter++)
439 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
440 {
441 // AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)hits->At(hit_counter);
442 AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
443 // if ( currentHit != firstHit )
444 if(cHit != fTrack->firstHit)// hits->First())
445 {
446 dx = cHit->GetX() - previousHit->GetX() ;
447 dy = cHit->GetY() - previousHit->GetY() ;
448 dpsi = 0.5 * (Double_t)sqrt ( dx*dx + dy*dy ) / radius ;
449 fTrack->SetPsierr(dpsi);
450 s = previousHit->GetS() - 2.0 * radius * (Double_t)asin ( dpsi ) ;
451 cHit->SetS(s);
452 }
453 else
454 cHit->SetS(total_s);
455 // cHit->s = total_s ;
456
457 sum += cHit->GetZWeight() ;
458 ss += cHit->GetZWeight() * cHit->GetS() ;
459 sz += cHit->GetZWeight() * cHit->GetZ() ;
460 sss += cHit->GetZWeight() * cHit->GetS() * cHit->GetS() ;
461 ssz += cHit->GetZWeight() * cHit->GetS() * cHit->GetZ() ;
462 previousHit = cHit ;
463 }
464
465 Double_t chi2,det = sum * sss - ss * ss;
466 if ( fabs(det) < 1e-20)
467 {
468 chi2 = 99999.F ;
469 fTrack->SetChiSq2(chi2);
470 return 0 ;
471 }
472
473 //Compute the best fitted parameters A,B
474 Double_t tanl,z0,dtanl,dz0;
475
476 tanl = (Double_t)((sum * ssz - ss * sz ) / det );
477 z0 = (Double_t)((sz * sss - ssz * ss ) / det );
478
479 fTrack->SetTgl(tanl);
480 fTrack->SetZ0(z0);
481
482 // calculate chi-square
483
484 chi2 = 0.;
485 Double_t r1 ;
486
487 //for(hit_counter=0; hit_counter<num_of_hits; hit_counter++)
488 for(fTrack->StartLoop(); fTrack->LoopDone(); fTrack->GetNextHit())
489 {
490 //AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)hits->At(hit_counter);
491 AliL3ConfMapPoint *cHit = (AliL3ConfMapPoint*)fTrack->currentHit;
492 r1 = cHit->GetZ() - tanl * cHit->GetS() - z0 ;
493 chi2 += (Double_t) ( (Double_t)cHit->GetZWeight() * (r1 * r1) );
494 }
495 fTrack->SetChiSq2(chi2);
496 //
497 // calculate estimated variance
498 // varsq=chi/(double(n)-2.)
499 // calculate covariance matrix
500 // siga=sqrt(varsq*sxx/det)
501 // sigb=sqrt(varsq*sum/det)
502 //
503 dtanl = (Double_t) ( sum / det );
504 dz0 = (Double_t) ( sss / det );
505
506 fTrack->SetTglerr(dtanl);
507 fTrack->SetZ0err(dz0);
508
509 return 0 ;
510}