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[u/mrichter/AliRoot.git] / HLT / src / AliL3Fitter.cxx
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1934a2f8 1//$Id$
2
3// Author: Anders Vestbo <mailto:vestbo@fi.uib.no>
4//*-- Copyright &copy ASV
5
6#include <math.h>
7
8#include "AliL3Defs.h"
9#include "AliL3Logging.h"
10#include "AliL3Fitter.h"
11#include "AliL3Vertex.h"
12#include "AliL3Track.h"
13#include "AliL3SpacePointData.h"
14#include "AliL3FileHandler.h"
15
16//_____________________________________________________________
17// AliL3Fitter
18//
19// Fit class HLT
20
21ClassImp(AliL3Fitter)
22
23AliL3Fitter::AliL3Fitter(AliL3Vertex *vertex)
24{
25 //constructor
26 fTrack=0;
27 fVertex = vertex;
28 BFACT = 0.0029980;
29 fVertexConstraint=kTRUE;
30}
31
32void AliL3Fitter::LoadClusters(Char_t *path)
33{
34 Char_t fname[256];
35 AliL3FileHandler *clusterfile[36][6];
36 for(Int_t s=0; s<=35; s++)
37 {
38 for(Int_t p=0; p<6; p++)
39 {
40 clusterfile[s][p] = new AliL3FileHandler();
41 sprintf(fname,"%spoints_%d_%d.raw",path,s,p);
42 if(!clusterfile[s][p]->SetBinaryInput(fname))
43 {
44 delete clusterfile[s][p];
45 clusterfile[s][p] = 0;
46 continue;
47 }
48 fClusters[s][p] = (AliL3SpacePointData*)clusterfile[s][p]->Allocate();
49 clusterfile[s][p]->Binary2Memory(fNcl[s][p],fClusters[s][p]);
50 clusterfile[s][p]->CloseBinaryInput();
51 }
52 }
53}
54
55Int_t AliL3Fitter::FitHelix(AliL3Track *track)
56{
57 fTrack = track;
58 if(FitCircle())
59 {
60 LOG(AliL3Log::kError,"AliL3Fitter::FitHelix","TrackFit")<<AliL3Log::kDec<<
61 "Problems during circle fit"<<ENDLOG;
62 return 1;
63 }
64 if(FitLine())
65 {
66 LOG(AliL3Log::kError,"AliL3Fitter::FitHelix","TrackFit")<<AliL3Log::kDec<<
67 "Problems during line fit"<<ENDLOG;
68 return 1;
69 }
70 return 0;
71}
72
73Int_t AliL3Fitter::FitCircle()
74{
75 //-----------------------------------------------------------------
76 //Fits circle parameters using algorithm
77 //described by ChErnov and Oskov in Computer Physics
78 //Communications.
79 //
80 //Written in FORTRAN by Jawluen Tang, Physics department , UT-Austin
81 //Moved to C by Pablo Yepes
82 //Moved to AliROOT by ASV.
83 //------------------------------------------------------------------
84
85 Double_t wsum = 0.0 ;
86 Double_t xav = 0.0 ;
87 Double_t yav = 0.0 ;
88
89 //
90 // Loop over hits calculating average
91
92 Double_t fXYWeight[(fTrack->GetNHits())];
93 UInt_t *hitnum = fTrack->GetHitNumbers();
94 for(Int_t i=0; i<fTrack->GetNHits(); i++)
95 {
96 UInt_t id = hitnum[i];
97 Int_t slice = (id>>25) & 0x7f;
98 Int_t patch = (id>>22) & 0x7;
99 UInt_t pos = id&0x3fffff;
100
101 AliL3SpacePointData *points = fClusters[slice][patch];
102 fXYWeight[i] = 1./ (Double_t)(points[pos].fXYErr*points[pos].fXYErr + points[pos].fXYErr*points[pos].fXYErr);
103 wsum += fXYWeight[i];
104 xav += fXYWeight[i]*points[pos].fX;
105 yav += fXYWeight[i]*points[pos].fY;
106
107 }
108 if (fVertexConstraint == kTRUE)
109 {
110 wsum += fVertex->GetXYWeight() ;
111 xav += fVertex->GetX() ;
112 yav += fVertex->GetY() ;
113 }
114
115 xav = xav / wsum ;
116 yav = yav / wsum ;
117//
118// CALCULATE <X**2>, <XY>, AND <Y**2> WITH <X> = 0, & <Y> = 0
119//
120 Double_t xxav = 0.0 ;
121 Double_t xyav = 0.0 ;
122 Double_t yyav = 0.0 ;
123 Double_t xi, yi ;
124
125 for(Int_t i=0; i<fTrack->GetNHits(); i++)
126 {
127 UInt_t id = hitnum[i];
128 Int_t slice = (id>>25) & 0x7f;
129 Int_t patch = (id>>22) & 0x7;
130 UInt_t pos = id&0x3fffff;
131 AliL3SpacePointData *points = fClusters[slice][patch];
132 xi = points[pos].fX -xav;
133 yi = points[pos].fY - yav ;
134 xxav += xi * xi * fXYWeight[i];
135 xyav += xi * yi * fXYWeight[i];
136 yyav += yi * yi * fXYWeight[i];
137 }
138
139 if (fVertexConstraint == kTRUE)
140 {
141 xi = fVertex->GetX() - xav ;
142 yi = fVertex->GetY() - yav ;
143 xxav += xi * xi * fVertex->GetXYWeight() ;
144 xyav += xi * yi * fVertex->GetXYWeight() ;
145 yyav += yi * yi * fVertex->GetXYWeight() ;
146 }
147 xxav = xxav / wsum ;
148 xyav = xyav / wsum ;
149 yyav = yyav / wsum ;
150//
151//--> ROTATE COORDINATES SO THAT <XY> = 0
152//
153//--> SIGN(C**2 - S**2) = SIGN(XXAV - YYAV) >
154//--> & > ==> NEW : (XXAV-YYAV) > 0
155//--> SIGN(S) = SIGN(XYAV) >
156
157 Double_t a = fabs( xxav - yyav ) ;
158 Double_t b = 4.0 * xyav * xyav ;
159
160 Double_t asqpb = a * a + b ;
161 Double_t rasqpb = sqrt ( asqpb) ;
162
163 Double_t splus = 1.0 + a / rasqpb ;
164 Double_t sminus = b / (asqpb * splus) ;
165
166 splus = sqrt (0.5 * splus ) ;
167 sminus = sqrt (0.5 * sminus) ;
168//
169//-> FIRST REQUIRE : SIGN(C**2 - S**2) = SIGN(XXAV - YYAV)
170//
171 Double_t sinrot, cosrot ;
172 if ( xxav <= yyav ) {
173 cosrot = sminus ;
174 sinrot = splus ;
175 }
176 else {
177 cosrot = splus ;
178 sinrot = sminus ;
179 }
180//
181//-> REQUIRE : SIGN(S) = SIGN(XYAV) * SIGN(C) (ASSUMING SIGN(C) > 0)
182//
183 if ( xyav < 0.0 ) sinrot = - sinrot ;
184//
185//--> WE NOW HAVE THE SMALLEST ANGLE THAT GUARANTEES <X**2> > <Y**2>
186//--> TO GET THE SIGN OF THE CHARGE RIGHT, THE NEW X-AXIS MUST POINT
187//--> OUTWARD FROM THE ORGIN. WE ARE FREE TO CHANGE SIGNS OF BOTH
188//--> COSROT AND SINROT SIMULTANEOUSLY TO ACCOMPLISH THIS.
189//
190//--> CHOOSE SIGN OF C WISELY TO BE ABLE TO GET THE SIGN OF THE CHARGE
191//
192 if ( cosrot*xav+sinrot*yav < 0.0 ) {
193 cosrot = -cosrot ;
194 sinrot = -sinrot ;
195 }
196//
197//-> NOW GET <R**2> AND RSCALE= SQRT(<R**2>)
198//
199 Double_t rrav = xxav + yyav ;
200 Double_t rscale = sqrt(rrav) ;
201
202 xxav = 0.0 ;
203 yyav = 0.0 ;
204 xyav = 0.0 ;
205 Double_t xrrav = 0.0 ;
206 Double_t yrrav = 0.0 ;
207 Double_t rrrrav = 0.0 ;
208
209 Double_t xixi, yiyi, riri, wiriri, xold, yold ;
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 AliL3SpacePointData *points = fClusters[slice][patch];
218
219 xold = points[pos].fX - xav ;
220 yold = points[pos].fY - yav ;
221 //
222 //--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
223 //
224 xi = ( cosrot * xold + sinrot * yold ) / rscale ;
225 yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
226
227 xixi = xi * xi ;
228 yiyi = yi * yi ;
229 riri = xixi + yiyi ;
230 wiriri = fXYWeight[i] * riri ;
231
232 xyav += fXYWeight[i] * xi * yi ;
233 xxav += fXYWeight[i] * xixi ;
234 yyav += fXYWeight[i] * yiyi ;
235
236 xrrav += wiriri * xi ;
237 yrrav += wiriri * yi ;
238 rrrrav += wiriri * riri ;
239 }
240 //
241// Include vertex if required
242//
243 if (fVertexConstraint == kTRUE)
244 {
245 xold = fVertex->GetX() - xav ;
246 yold = fVertex->GetY() - yav ;
247 //
248 //--> ROTATE SO THAT <XY> = 0 & DIVIDE BY RSCALE SO THAT <R**2> = 1
249 //
250 xi = ( cosrot * xold + sinrot * yold ) / rscale ;
251 yi = ( -sinrot * xold + cosrot * yold ) / rscale ;
252
253 xixi = xi * xi ;
254 yiyi = yi * yi ;
255 riri = xixi + yiyi ;
256 wiriri = fVertex->GetXYWeight() * riri ;
257
258 xyav += fVertex->GetXYWeight() * xi * yi ;
259 xxav += fVertex->GetXYWeight() * xixi ;
260 yyav += fVertex->GetXYWeight() * yiyi ;
261
262 xrrav += wiriri * xi ;
263 yrrav += wiriri * yi ;
264 rrrrav += wiriri * riri ;
265 }
266 //
267 //
268 //
269 //--> DIVIDE BY WSUM TO MAKE AVERAGES
270 //
271 xxav = xxav / wsum ;
272 yyav = yyav / wsum ;
273 xrrav = xrrav / wsum ;
274 yrrav = yrrav / wsum ;
275 rrrrav = rrrrav / wsum ;
276 xyav = xyav / wsum ;
277
278 Int_t const ntry = 5 ;
279//
280//--> USE THESE TO GET THE COEFFICIENTS OF THE 4-TH ORDER POLYNIMIAL
281//--> DON'T PANIC - THE THIRD ORDER TERM IS ZERO !
282//
283 Double_t xrrxrr = xrrav * xrrav ;
284 Double_t yrryrr = yrrav * yrrav ;
285 Double_t rrrrm1 = rrrrav - 1.0 ;
286 Double_t xxyy = xxav * yyav ;
287
288 Double_t c0 = rrrrm1*xxyy - xrrxrr*yyav - yrryrr*xxav ;
289 Double_t c1 = - rrrrm1 + xrrxrr + yrryrr - 4.0*xxyy ;
290 Double_t c2 = 4.0 + rrrrm1 - 4.0*xxyy ;
291 Double_t c4 = - 4.0 ;
292//
293//--> COEFFICIENTS OF THE DERIVATIVE - USED IN NEWTON-RAPHSON ITERATIONS
294//
295 Double_t c2d = 2.0 * c2 ;
296 Double_t c4d = 4.0 * c4 ;
297//
298//--> 0'TH VALUE OF LAMDA - LINEAR INTERPOLATION BETWEEN P(0) & P(YYAV)
299//
300// LAMDA = YYAV * C0 / (C0 + YRRSQ * (XXAV-YYAV))
301 Double_t lamda = 0.0 ;
302 Double_t dlamda = 0.0 ;
303//
304 Double_t chiscl = wsum * rscale * rscale ;
305 Double_t dlamax = 0.001 / chiscl ;
306
307 Double_t p, pd ;
308 for ( int itry = 1 ; itry <= ntry ; itry++ ) {
309 p = c0 + lamda * (c1 + lamda * (c2 + lamda * lamda * c4 )) ;
310 pd = (c1 + lamda * (c2d + lamda * lamda * c4d)) ;
311 dlamda = -p / pd ;
312 lamda = lamda + dlamda ;
313 if (fabs(dlamda)< dlamax) break ;
314 }
315
316 Double_t chi2 = (Double_t)(chiscl * lamda) ;
317
318 //fTrack->SetChiSq1(chi2);
319 // Double_t dchisq = chiscl * dlamda ;
320//
321//--> NOW CALCULATE THE MATRIX ELEMENTS FOR ALPHA, BETA & KAPPA
322//
323 Double_t h11 = xxav - lamda ;
324 Double_t h14 = xrrav ;
325 Double_t h22 = yyav - lamda ;
326 Double_t h24 = yrrav ;
327 Double_t h34 = 1.0 + 2.0*lamda ;
328 if ( h11 == 0.0 || h22 == 0.0 ){
329 LOG(AliL3Log::kError,"AliL3Fitter::FitCircle","TrackFit")<<AliL3Log::kDec<<
330 "Problems fitting circle"<<ENDLOG;
331 return 1 ;
332 }
333 Double_t rootsq = (h14*h14)/(h11*h11) + 4.0*h34 ;
334
335 Double_t ratio, kappa, beta ;
336 if ( fabs(h22) > fabs(h24) ) {
337 ratio = h24 / h22 ;
338 rootsq = ratio * ratio + rootsq ;
339 kappa = 1.0 / sqrt(rootsq) ;
340 beta = - ratio * kappa ;
341 }
342 else {
343 ratio = h22 / h24 ;
344 rootsq = 1.0 + ratio * ratio * rootsq ;
345 beta = 1.0 / sqrt(rootsq) ;
346 if ( h24 > 0 ) beta = - beta ;
347 kappa = -ratio * beta ;
348 }
349 Double_t alpha = - (h14/h11) * kappa ;
350//
351//--> transform these into the lab coordinate system
352//--> first get kappa and back to real dimensions
353//
354 Double_t kappa1 = kappa / rscale ;
355 Double_t dbro = 0.5 / kappa1 ;
356//
357//--> next rotate alpha and beta and scale
358//
359 Double_t alphar = (cosrot * alpha - sinrot * beta)* dbro ;
360 Double_t betar = (sinrot * alpha + cosrot * beta)* dbro ;
361//
362//--> then translate by (xav,yav)
363//
364 Double_t acent = (double)(xav - alphar) ;
365 Double_t bcent = (double)(yav - betar ) ;
366 Double_t radius = (double)dbro ;
367//
368// Get charge
369//
370 Int_t q = ( ( yrrav < 0 ) ? 1 : -1 ) ;
371
372 fTrack->SetCharge(q);
373
374//
375// Get other track parameters
376//
377 Double_t x0, y0,phi0,r0,psi,pt ;
378 if ( fVertexConstraint == kTRUE)
379 {
380 //flag = 1 ; // primary track flag
381 x0 = fVertex->GetX() ;
382 y0 = fVertex->GetY() ;
383 phi0 = fVertex->GetPhi() ;
384 r0 = fVertex->GetR() ;
385 fTrack->SetPhi0(phi0);
386 fTrack->SetR0(r0);
387 }
388 else
389 {
390 Int_t lastid=fTrack->GetNHits()-1;
391 UInt_t id = hitnum[lastid];
392 Int_t slice = (id>>25) & 0x7f;
393 Int_t patch = (id>>22) & 0x7;
394 UInt_t pos = id&0x3fffff;
395 AliL3SpacePointData *points = fClusters[slice][patch];
396
397 //flag = 0 ; // primary track flag
398 x0 = points[pos].fX;
399 y0 = points[pos].fY;
400 phi0 = atan2(points[pos].fY,points[pos].fX);
401 if ( phi0 < 0 ) phi0 += 2*Pi;
402 r0 = sqrt ( points[pos].fX * points[pos].fX + points[pos].fY*points[pos].fY);
403 fTrack->SetPhi0(phi0);
404 fTrack->SetR0(r0);
405 }
406 //
407 psi = (Double_t)atan2(bcent-y0,acent-x0) ;
408 psi = psi + q * 0.5F * Pi ;
409 if ( psi < 0 ) psi = psi + 2*Pi;
410
411 pt = (Double_t)(BFACT * BField * radius ) ;
412 fTrack->SetPsi(psi);
413 fTrack->SetPt(pt);
414 fTrack->SetFirstPoint(x0,y0,0);
415 //
416// Get errors from fast fit
417//
418 //if ( getPara()->getErrors ) getErrorsCircleFit ( acent, bcent, radius ) ;
419//
420 return 0 ;
421
422}
423
424//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
425// Fit Line in s-z plane
426//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
427Int_t AliL3Fitter::FitLine ( )
428{
429 //
430 //Initialization
431 //
432 Double_t sum = 0.F ;
433 Double_t ss = 0.F ;
434 Double_t sz = 0.F ;
435 Double_t sss = 0.F ;
436 Double_t ssz = 0.F ;
437 //
438 //find sum , sums ,sumz, sumss
439 //
440 Double_t dx, dy ;
441 Double_t radius = (Double_t)(fTrack->GetPt() / ( BFACT * BField ) ) ;
442
443 //TObjArray *hits = fTrack->GetHits();
444 //Int_t num_of_hits = fTrack->GetNumberOfPoints();
445
446 Double_t fS[(fTrack->GetNHits())];
447 UInt_t *hitnum = fTrack->GetHitNumbers();
448 if (fVertexConstraint==kTRUE)
449 {
450 UInt_t id = hitnum[0];
451 Int_t slice = (id>>25) & 0x7f;
452 Int_t patch = (id>>22) & 0x7;
453 UInt_t pos = id&0x3fffff;
454 AliL3SpacePointData *points = fClusters[slice][patch];
455
456 dx = points[pos].fX - fVertex->GetX();
457 dy = points[pos].fY - fVertex->GetY() ;
458 }
459 else
460 {
461 UInt_t id = hitnum[0];
462 Int_t slice = (id>>25) & 0x7f;
463 Int_t patch = (id>>22) & 0x7;
464 UInt_t posf = id&0x3fffff;
465 AliL3SpacePointData *pointsf = fClusters[slice][patch];
466 id = hitnum[(fTrack->GetNHits()-1)];
467 slice = (id>>25) & 0x7f;
468 patch = (id>>22) & 0x7;
469 UInt_t posl = id&0x3fffff;
470 AliL3SpacePointData *pointsl = fClusters[slice][patch];
471 dx = pointsf[posf].fX - pointsl[posl].fX;
472 dy = pointsf[posf].fY - pointsl[posl].fY;
473
474 }
475
476 Double_t localPsi = 0.5F * sqrt ( dx*dx + dy*dy ) / radius ;
477 Double_t total_s ;
478
479 if ( fabs(localPsi) < 1. )
480 {
481 total_s = 2.0 * radius * asin ( localPsi ) ;
482 }
483 else
484 {
485 total_s = 2.0 * radius * Pi ;
486 }
487
488 Double_t dpsi,s;
489
490 for(Int_t i=0; i<fTrack->GetNHits(); i++)
491 {
492 UInt_t id = hitnum[i];
493 Int_t slice = (id>>25) & 0x7f;
494 Int_t patch = (id>>22) & 0x7;
495 UInt_t pos = id&0x3fffff;
496 AliL3SpacePointData *points = fClusters[slice][patch];
497
498 if(i>0)
499 {
500 id = hitnum[i-1];
501 slice = (id>>25) & 0x7f;
502 patch = (id>>22) & 0x7;
503 UInt_t lastpos = id&0x3fffff;
504 AliL3SpacePointData *lastpoints = fClusters[slice][patch];
505 dx = points[pos].fX -lastpoints[lastpos].fX;
506 dy = points[pos].fY -lastpoints[lastpos].fY;
507 dpsi = 0.5 * (Double_t)sqrt ( dx*dx + dy*dy ) / radius ;
508 fTrack->SetPsierr(dpsi);
509 s = fS[i-1] - 2.0 * radius * (Double_t)asin ( dpsi ) ;
510 fS[i]=s;
511 }
512 else
513 fS[i]=total_s;
514
515 sum += 1/(points[pos].fZErr*points[pos].fZErr);
516 ss += 1/(points[pos].fZErr*points[pos].fZErr) * fS[i];
517 sz += 1/(points[pos].fZErr*points[pos].fZErr)*points[pos].fZ;
518 sss += 1/(points[pos].fZErr*points[pos].fZErr)* fS[i] * fS[i];
519 ssz += 1/(points[pos].fZErr*points[pos].fZErr) * fS[i] * points[pos].fZ;
520
521 }
522
523
524 Double_t chi2,det = sum * sss - ss * ss;
525 if ( fabs(det) < 1e-20)
526 {
527 chi2 = 99999.F ;
528 //fTrack->SetChiSq2(chi2);
529 return 0 ;
530 }
531
532 //Compute the best fitted parameters A,B
533 Double_t tanl,z0,dtanl,dz0;
534
535 tanl = (Double_t)((sum * ssz - ss * sz ) / det );
536 z0 = (Double_t)((sz * sss - ssz * ss ) / det );
537
538 fTrack->SetTgl(tanl);
539 fTrack->SetZ0(z0);
540
541 // calculate chi-square
542
543 chi2 = 0.;
544 Double_t r1 ;
545
546 for(Int_t i=0; i<fTrack->GetNHits(); i++)
547 {
548 UInt_t id = hitnum[i];
549 Int_t slice = (id>>25) & 0x7f;
550 Int_t patch = (id>>22) & 0x7;
551 UInt_t pos = id&0x3fffff;
552 AliL3SpacePointData *points = fClusters[slice][patch];
553 r1 = points[pos].fZ - tanl * fS[i] - z0 ;
554 chi2 += (Double_t) ( (Double_t)(1/(points[pos].fZErr*points[pos].fZErr)) * (r1 * r1) );
555 }
556
557 //fTrack->SetChiSq2(chi2);
558 //
559 // calculate estimated variance
560 // varsq=chi/(double(n)-2.)
561 // calculate covariance matrix
562 // siga=sqrt(varsq*sxx/det)
563 // sigb=sqrt(varsq*sum/det)
564 //
565 dtanl = (Double_t) ( sum / det );
566 dz0 = (Double_t) ( sss / det );
567
568 fTrack->SetTglerr(dtanl);
569 fTrack->SetZ0err(dz0);
570
571 return 0 ;
572}