Corrected protection.
[u/mrichter/AliRoot.git] / STEER / AliTrackerBase.cxx
CommitLineData
4811a3f4 1/**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
3 * *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
6 * *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
15
16/* $Id: AliTrackerBase.cxx 38069 2009-12-24 16:56:18Z belikov $ */
17
18//-------------------------------------------------------------------------
19// Implementation of the AliTrackerBase class
075f4221 20// that is the base for the AliTracker class
21// Origin: Marian.Ivanov@cern.ch
4811a3f4 22//-------------------------------------------------------------------------
23#include <TClass.h>
24#include <TMath.h>
25#include <TGeoManager.h>
26
27#include "AliLog.h"
28#include "AliTrackerBase.h"
29#include "AliExternalTrackParam.h"
075f4221 30#include "AliTrackPointArray.h"
363db7c3 31#include "TVectorD.h"
4811a3f4 32
33extern TGeoManager *gGeoManager;
34
35ClassImp(AliTrackerBase)
36
37AliTrackerBase::AliTrackerBase():
38 TObject(),
39 fX(0),
40 fY(0),
41 fZ(0),
42 fSigmaX(0.005),
43 fSigmaY(0.005),
44 fSigmaZ(0.010)
45{
46 //--------------------------------------------------------------------
47 // The default constructor.
48 //--------------------------------------------------------------------
49 if (!TGeoGlobalMagField::Instance()->GetField())
50 AliWarning("Field map is not set.");
51}
52
53//__________________________________________________________________________
54AliTrackerBase::AliTrackerBase(const AliTrackerBase &atr):
55 TObject(atr),
56 fX(atr.fX),
57 fY(atr.fY),
58 fZ(atr.fZ),
59 fSigmaX(atr.fSigmaX),
60 fSigmaY(atr.fSigmaY),
61 fSigmaZ(atr.fSigmaZ)
62{
63 //--------------------------------------------------------------------
64 // The default constructor.
65 //--------------------------------------------------------------------
66 if (!TGeoGlobalMagField::Instance()->GetField())
67 AliWarning("Field map is not set.");
68}
69
70//__________________________________________________________________________
71Double_t AliTrackerBase::GetBz()
72{
73 AliMagF* fld = (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
74 if (!fld) return 0.5*kAlmost0Field;
75 Double_t bz = fld->SolenoidField();
76 return TMath::Sign(0.5*kAlmost0Field,bz) + bz;
77}
78
79//__________________________________________________________________________
80Double_t AliTrackerBase::GetBz(const Double_t *r) {
81 //------------------------------------------------------------------
82 // Returns Bz (kG) at the point "r" .
83 //------------------------------------------------------------------
84 AliMagF* fld = (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
85 if (!fld) return 0.5*kAlmost0Field;
86 Double_t bz = fld->GetBz(r);
87 return TMath::Sign(0.5*kAlmost0Field,bz) + bz;
88}
89
90//__________________________________________________________________________
91void AliTrackerBase::GetBxByBz(const Double_t r[3], Double_t b[3]) {
92 //------------------------------------------------------------------
93 // Returns Bx, By and Bz (kG) at the point "r" .
94 //------------------------------------------------------------------
95 AliMagF* fld = (AliMagF*)TGeoGlobalMagField::Instance()->GetField();
96 if (!fld) {
97 b[0] = b[1] = 0.;
98 b[2] = 0.5*kAlmost0Field;
99 return;
100 }
101
102 if (fld->IsUniform()) {
103 b[0] = b[1] = 0.;
104 b[2] = fld->SolenoidField();
105 } else {
106 fld->Field(r,b);
107 }
108 b[2] = (TMath::Sign(0.5*kAlmost0Field,b[2]) + b[2]);
109 return;
110}
111
112Double_t AliTrackerBase::MeanMaterialBudget(const Double_t *start, const Double_t *end, Double_t *mparam)
113{
114 //
115 // Calculate mean material budget and material properties between
116 // the points "start" and "end".
117 //
118 // "mparam" - parameters used for the energy and multiple scattering
119 // corrections:
120 //
121 // mparam[0] - mean density: sum(x_i*rho_i)/sum(x_i) [g/cm3]
122 // mparam[1] - equivalent rad length fraction: sum(x_i/X0_i) [adimensional]
123 // mparam[2] - mean A: sum(x_i*A_i)/sum(x_i) [adimensional]
124 // mparam[3] - mean Z: sum(x_i*Z_i)/sum(x_i) [adimensional]
125 // mparam[4] - length: sum(x_i) [cm]
126 // mparam[5] - Z/A mean: sum(x_i*Z_i/A_i)/sum(x_i) [adimensional]
127 // mparam[6] - number of boundary crosses
128 //
129 // Origin: Marian Ivanov, Marian.Ivanov@cern.ch
130 //
131 // Corrections and improvements by
132 // Andrea Dainese, Andrea.Dainese@lnl.infn.it,
133 // Andrei Gheata, Andrei.Gheata@cern.ch
134 //
135
136 mparam[0]=0; mparam[1]=1; mparam[2] =0; mparam[3] =0;
137 mparam[4]=0; mparam[5]=0; mparam[6]=0;
138 //
139 Double_t bparam[6]; // total parameters
140 Double_t lparam[6]; // local parameters
141
142 for (Int_t i=0;i<6;i++) bparam[i]=0;
143
144 if (!gGeoManager) {
145 AliErrorClass("No TGeo\n");
146 return 0.;
147 }
148 //
149 Double_t length;
150 Double_t dir[3];
151 length = TMath::Sqrt((end[0]-start[0])*(end[0]-start[0])+
152 (end[1]-start[1])*(end[1]-start[1])+
153 (end[2]-start[2])*(end[2]-start[2]));
154 mparam[4]=length;
155 if (length<TGeoShape::Tolerance()) return 0.0;
156 Double_t invlen = 1./length;
157 dir[0] = (end[0]-start[0])*invlen;
158 dir[1] = (end[1]-start[1])*invlen;
159 dir[2] = (end[2]-start[2])*invlen;
160
161 // Initialize start point and direction
162 TGeoNode *currentnode = 0;
163 TGeoNode *startnode = gGeoManager->InitTrack(start, dir);
164 if (!startnode) {
165 AliErrorClass(Form("start point out of geometry: x %f, y %f, z %f",
166 start[0],start[1],start[2]));
167 return 0.0;
168 }
169 TGeoMaterial *material = startnode->GetVolume()->GetMedium()->GetMaterial();
170 lparam[0] = material->GetDensity();
171 lparam[1] = material->GetRadLen();
172 lparam[2] = material->GetA();
173 lparam[3] = material->GetZ();
174 lparam[4] = length;
175 lparam[5] = lparam[3]/lparam[2];
176 if (material->IsMixture()) {
177 TGeoMixture * mixture = (TGeoMixture*)material;
178 lparam[5] =0;
179 Double_t sum =0;
180 for (Int_t iel=0;iel<mixture->GetNelements();iel++){
181 sum += mixture->GetWmixt()[iel];
182 lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
183 }
184 lparam[5]/=sum;
185 }
186
187 // Locate next boundary within length without computing safety.
188 // Propagate either with length (if no boundary found) or just cross boundary
189 gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
190 Double_t step = 0.0; // Step made
191 Double_t snext = gGeoManager->GetStep();
192 // If no boundary within proposed length, return current density
193 if (!gGeoManager->IsOnBoundary()) {
194 mparam[0] = lparam[0];
195 mparam[1] = lparam[4]/lparam[1];
196 mparam[2] = lparam[2];
197 mparam[3] = lparam[3];
198 mparam[4] = lparam[4];
199 return lparam[0];
200 }
201 // Try to cross the boundary and see what is next
202 Int_t nzero = 0;
203 while (length>TGeoShape::Tolerance()) {
204 currentnode = gGeoManager->GetCurrentNode();
205 if (snext<2.*TGeoShape::Tolerance()) nzero++;
206 else nzero = 0;
207 if (nzero>3) {
208 // This means navigation has problems on one boundary
209 // Try to cross by making a small step
210 AliErrorClass("Cannot cross boundary\n");
211 mparam[0] = bparam[0]/step;
212 mparam[1] = bparam[1];
213 mparam[2] = bparam[2]/step;
214 mparam[3] = bparam[3]/step;
215 mparam[5] = bparam[5]/step;
216 mparam[4] = step;
217 mparam[0] = 0.; // if crash of navigation take mean density 0
218 mparam[1] = 1000000; // and infinite rad length
219 return bparam[0]/step;
220 }
221 mparam[6]+=1.;
222 step += snext;
223 bparam[1] += snext/lparam[1];
224 bparam[2] += snext*lparam[2];
225 bparam[3] += snext*lparam[3];
226 bparam[5] += snext*lparam[5];
227 bparam[0] += snext*lparam[0];
228
229 if (snext>=length) break;
230 if (!currentnode) break;
231 length -= snext;
232 material = currentnode->GetVolume()->GetMedium()->GetMaterial();
233 lparam[0] = material->GetDensity();
234 lparam[1] = material->GetRadLen();
235 lparam[2] = material->GetA();
236 lparam[3] = material->GetZ();
237 lparam[5] = lparam[3]/lparam[2];
238 if (material->IsMixture()) {
239 TGeoMixture * mixture = (TGeoMixture*)material;
240 lparam[5]=0;
241 Double_t sum =0;
242 for (Int_t iel=0;iel<mixture->GetNelements();iel++){
243 sum+= mixture->GetWmixt()[iel];
244 lparam[5]+= mixture->GetZmixt()[iel]*mixture->GetWmixt()[iel]/mixture->GetAmixt()[iel];
245 }
246 lparam[5]/=sum;
247 }
248 gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
249 snext = gGeoManager->GetStep();
250 }
251 mparam[0] = bparam[0]/step;
252 mparam[1] = bparam[1];
253 mparam[2] = bparam[2]/step;
254 mparam[3] = bparam[3]/step;
255 mparam[5] = bparam[5]/step;
256 return bparam[0]/step;
257}
258
259
260Bool_t
261AliTrackerBase::PropagateTrackTo(AliExternalTrackParam *track, Double_t xToGo,
262 Double_t mass, Double_t maxStep, Bool_t rotateTo, Double_t maxSnp, Double_t sign){
263 //----------------------------------------------------------------
264 //
265 // Propagates the track to the plane X=xk (cm) using the magnetic field map
266 // and correcting for the crossed material.
267 //
268 // mass - mass used in propagation - used for energy loss correction
269 // maxStep - maximal step for propagation
270 //
271 // Origin: Marian Ivanov, Marian.Ivanov@cern.ch
272 //
273 //----------------------------------------------------------------
274 const Double_t kEpsilon = 0.00001;
275 Double_t xpos = track->GetX();
276 Double_t dir = (xpos<xToGo) ? 1.:-1.;
277 //
278 while ( (xToGo-xpos)*dir > kEpsilon){
279 Double_t step = dir*TMath::Min(TMath::Abs(xToGo-xpos), maxStep);
280 Double_t x = xpos+step;
281 Double_t xyz0[3],xyz1[3],param[7];
282 track->GetXYZ(xyz0); //starting global position
283
284 Double_t bz=GetBz(xyz0); // getting the local Bz
285
286 if (!track->GetXYZAt(x,bz,xyz1)) return kFALSE; // no prolongation
287 xyz1[2]+=kEpsilon; // waiting for bug correction in geo
288
289 if (TMath::Abs(track->GetSnpAt(x,bz)) >= maxSnp) return kFALSE;
290 if (!track->PropagateTo(x,bz)) return kFALSE;
291
292 MeanMaterialBudget(xyz0,xyz1,param);
293 Double_t xrho=param[0]*param[4]*sign, xx0=param[1];
294
295 if (!track->CorrectForMeanMaterial(xx0,xrho,mass)) return kFALSE;
296 if (rotateTo){
297 if (TMath::Abs(track->GetSnp()) >= maxSnp) return kFALSE;
298 track->GetXYZ(xyz0); // global position
299 Double_t alphan = TMath::ATan2(xyz0[1], xyz0[0]);
300 //
301 Double_t ca=TMath::Cos(alphan-track->GetAlpha()),
302 sa=TMath::Sin(alphan-track->GetAlpha());
303 Double_t sf=track->GetSnp(), cf=TMath::Sqrt((1.-sf)*(1.+sf));
304 Double_t sinNew = sf*ca - cf*sa;
305 if (TMath::Abs(sinNew) >= maxSnp) return kFALSE;
306 if (!track->Rotate(alphan)) return kFALSE;
307 }
308 xpos = track->GetX();
309 }
310 return kTRUE;
311}
312
313Bool_t
314AliTrackerBase::PropagateTrackToBxByBz(AliExternalTrackParam *track,
315Double_t xToGo,
316 Double_t mass, Double_t maxStep, Bool_t rotateTo, Double_t maxSnp,Double_t sign){
317 //----------------------------------------------------------------
318 //
319 // Propagates the track to the plane X=xk (cm)
320 // taking into account all the three components of the magnetic field
321 // and correcting for the crossed material.
322 //
323 // mass - mass used in propagation - used for energy loss correction
324 // maxStep - maximal step for propagation
325 //
326 // Origin: Marian Ivanov, Marian.Ivanov@cern.ch
327 //
328 //----------------------------------------------------------------
329 const Double_t kEpsilon = 0.00001;
330 Double_t xpos = track->GetX();
331 Double_t dir = (xpos<xToGo) ? 1.:-1.;
332 //
333 while ( (xToGo-xpos)*dir > kEpsilon){
334 Double_t step = dir*TMath::Min(TMath::Abs(xToGo-xpos), maxStep);
335 Double_t x = xpos+step;
336 Double_t xyz0[3],xyz1[3],param[7];
337 track->GetXYZ(xyz0); //starting global position
338
339 Double_t b[3]; GetBxByBz(xyz0,b); // getting the local Bx, By and Bz
340
341 if (!track->GetXYZAt(x,b[2],xyz1)) return kFALSE; // no prolongation
342 xyz1[2]+=kEpsilon; // waiting for bug correction in geo
343
344 if (TMath::Abs(track->GetSnpAt(x,b[2])) >= maxSnp) return kFALSE;
345 if (!track->PropagateToBxByBz(x,b)) return kFALSE;
346
347 MeanMaterialBudget(xyz0,xyz1,param);
348 Double_t xrho=param[0]*param[4]*sign, xx0=param[1];
349
350 if (!track->CorrectForMeanMaterial(xx0,xrho,mass)) return kFALSE;
351 if (rotateTo){
352 if (TMath::Abs(track->GetSnp()) >= maxSnp) return kFALSE;
353 track->GetXYZ(xyz0); // global position
354 Double_t alphan = TMath::ATan2(xyz0[1], xyz0[0]);
355 //
356 Double_t ca=TMath::Cos(alphan-track->GetAlpha()),
357 sa=TMath::Sin(alphan-track->GetAlpha());
358 Double_t sf=track->GetSnp(), cf=TMath::Sqrt((1.-sf)*(1.+sf));
359 Double_t sinNew = sf*ca - cf*sa;
360 if (TMath::Abs(sinNew) >= maxSnp) return kFALSE;
361 if (!track->Rotate(alphan)) return kFALSE;
362 }
363 xpos = track->GetX();
364 }
365 return kTRUE;
366}
367
368Double_t AliTrackerBase::GetTrackPredictedChi2(AliExternalTrackParam *track,
369 Double_t mass, Double_t step,
370 const AliExternalTrackParam *backup) {
371 //
372 // This function brings the "track" with particle "mass" [GeV]
373 // to the same local coord. system and the same reference plane as
374 // of the "backup", doing it in "steps" [cm].
375 // Then, it calculates the 5D predicted Chi2 for these two tracks
376 //
377 Double_t chi2=kVeryBig;
378 Double_t alpha=backup->GetAlpha();
379 if (!track->Rotate(alpha)) return chi2;
380
381 Double_t xb=backup->GetX();
382 Double_t sign=(xb < track->GetX()) ? 1. : -1.;
383 if (!PropagateTrackTo(track,xb,mass,step,kFALSE,kAlmost1,sign)) return chi2;
384
385 chi2=track->GetPredictedChi2(backup);
386
387 return chi2;
388}
075f4221 389
390
391
392
393Double_t AliTrackerBase::MakeC(Double_t x1,Double_t y1,
394 Double_t x2,Double_t y2,
395 Double_t x3,Double_t y3)
396{
397 //-----------------------------------------------------------------
398 // Initial approximation of the track curvature
399 //-----------------------------------------------------------------
400 x3 -=x1;
401 x2 -=x1;
402 y3 -=y1;
403 y2 -=y1;
404 //
405 Double_t det = x3*y2-x2*y3;
406 if (TMath::Abs(det)<1e-10) {
407 return 0;
408 }
409 //
410 Double_t u = 0.5* (x2*(x2-x3)+y2*(y2-y3))/det;
411 Double_t x0 = x3*0.5-y3*u;
412 Double_t y0 = y3*0.5+x3*u;
413 Double_t c2 = 1/TMath::Sqrt(x0*x0+y0*y0);
414 if (det>0) c2*=-1;
415 return c2;
416}
417
418Double_t AliTrackerBase::MakeSnp(Double_t x1,Double_t y1,
419 Double_t x2,Double_t y2,
420 Double_t x3,Double_t y3)
421{
422 //-----------------------------------------------------------------
423 // Initial approximation of the track snp
424 //-----------------------------------------------------------------
425 x3 -=x1;
426 x2 -=x1;
427 y3 -=y1;
428 y2 -=y1;
429 //
430 Double_t det = x3*y2-x2*y3;
431 if (TMath::Abs(det)<1e-10) {
432 return 0;
433 }
434 //
435 Double_t u = 0.5* (x2*(x2-x3)+y2*(y2-y3))/det;
436 Double_t x0 = x3*0.5-y3*u;
437 Double_t y0 = y3*0.5+x3*u;
438 Double_t c2 = 1./TMath::Sqrt(x0*x0+y0*y0);
439 x0*=c2;
440 x0=TMath::Abs(x0);
441 if (y2*x2<0.) x0*=-1;
442 return x0;
443}
444
445Double_t AliTrackerBase::MakeTgl(Double_t x1,Double_t y1,
446 Double_t x2,Double_t y2,
447 Double_t z1,Double_t z2, Double_t c)
448{
449 //-----------------------------------------------------------------
450 // Initial approximation of the tangent of the track dip angle
451 //-----------------------------------------------------------------
452 //
453 x2-=x1;
454 y2-=y1;
455 z2-=z1;
456 Double_t d = TMath::Sqrt(x2*x2+y2*y2); // distance straight line
457 if (TMath::Abs(d*c*0.5)>1) return 0;
458 Double_t angle2 = TMath::ASin(d*c*0.5);
459 angle2 = z2*TMath::Abs(c/(angle2*2.));
460 return angle2;
461}
462
463
464Double_t AliTrackerBase::MakeTgl(Double_t x1,Double_t y1,
465 Double_t x2,Double_t y2,
466 Double_t z1,Double_t z2)
467{
468 //-----------------------------------------------------------------
469 // Initial approximation of the tangent of the track dip angle
470 //-----------------------------------------------------------------
471 return (z1 - z2)/sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
472}
473
474
475AliExternalTrackParam * AliTrackerBase::MakeSeed( AliTrackPoint &point0, AliTrackPoint &point1, AliTrackPoint &point2){
476 //
477 // Make Seed - AliExternalTrackParam from input 3 points
478 // returning seed in local frame of point0
479 //
480 Double_t xyz0[3]={0,0,0};
481 Double_t xyz1[3]={0,0,0};
482 Double_t xyz2[3]={0,0,0};
483 Double_t alpha=point0.GetAngle();
484 Double_t xyz[3]={point0.GetX(),point0.GetY(),point0.GetZ()};
485 Double_t bxyz[3]; GetBxByBz(xyz,bxyz);
486 Double_t bz = bxyz[2];
487 //
488 // get points in frame of point 0
489 //
490 AliTrackPoint p0r = point0.Rotate(alpha);
491 AliTrackPoint p1r = point1.Rotate(alpha);
492 AliTrackPoint p2r = point2.Rotate(alpha);
493 xyz0[0]=p0r.GetX();
494 xyz0[1]=p0r.GetY();
495 xyz0[2]=p0r.GetZ();
496 xyz1[0]=p1r.GetX();
497 xyz1[1]=p1r.GetY();
498 xyz1[2]=p1r.GetZ();
499 xyz2[0]=p2r.GetX();
500 xyz2[1]=p2r.GetY();
501 xyz2[2]=p2r.GetZ();
502 //
503 // make covariance estimate
504 //
505 Double_t covar[15];
506 Double_t param[5]={0,0,0,0,0};
507 for (Int_t m=0; m<15; m++) covar[m]=0;
508 //
509 // calculate intitial param
510 param[0]=xyz0[1];
511 param[1]=xyz0[2];
512 param[2]=MakeSnp(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz2[0],xyz2[1]);
513 param[4]=MakeC(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz2[0],xyz2[1]);
514 param[3]=MakeTgl(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz0[2],xyz1[2],param[4]);
515
516 //covariance matrix - only diagonal elements
517 //Double_t dist=p0r.GetX()-p2r.GetX();
518 Double_t deltaP=0;
519 covar[0]= p0r.GetCov()[3];
520 covar[2]= p0r.GetCov()[5];
521 //sigma snp
522 deltaP= (MakeSnp(xyz0[0],xyz0[1]+TMath::Sqrt(p0r.GetCov()[3]),xyz1[0],xyz1[1],xyz2[0],xyz2[1])-param[2]);
523 covar[5]+= deltaP*deltaP;
524 deltaP= (MakeSnp(xyz0[0],xyz0[1],xyz1[0],xyz1[1]+TMath::Sqrt(p1r.GetCov()[3]),xyz2[0],xyz2[1])-param[2]);
525 covar[5]+= deltaP*deltaP;
526 deltaP= (MakeSnp(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz2[0],xyz2[1]+TMath::Sqrt(p1r.GetCov()[3]))-param[2]);
527 covar[5]+= deltaP*deltaP;
528 //sigma tgl
529 //
530 deltaP=MakeTgl(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz0[2]+TMath::Sqrt(p1r.GetCov()[5]),xyz1[2],param[4])-param[3];
531 covar[9]+= deltaP*deltaP;
532 deltaP=MakeTgl(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz0[2],xyz1[2]+TMath::Sqrt(p1r.GetCov()[5]),param[4])-param[3];
533 covar[9]+= deltaP*deltaP;
534 //
535
536 deltaP=MakeC(xyz0[0],xyz0[1]+TMath::Sqrt(p0r.GetCov()[3]),xyz1[0],xyz1[1],xyz2[0],xyz2[1])-param[4];
537 covar[14]+= deltaP*deltaP;
538 deltaP=MakeC(xyz0[0],xyz0[1],xyz1[0],xyz1[1]+TMath::Sqrt(p1r.GetCov()[3]),xyz2[0],xyz2[1])-param[4];
539 covar[14]+= deltaP*deltaP;
540 deltaP=MakeC(xyz0[0],xyz0[1],xyz1[0],xyz1[1],xyz2[0],xyz2[1]+TMath::Sqrt(p2r.GetCov()[3]))-param[4];
541 covar[14]+= deltaP*deltaP;
542
543 covar[14]/=(bz*kB2C)*(bz*kB2C);
544 param[4]/=(bz*kB2C); // transform to 1/pt
545 AliExternalTrackParam * trackParam = new AliExternalTrackParam(xyz0[0],alpha,param, covar);
546 if (0) {
547 // consistency check -to put warnings here
548 // small disagrement once Track extrapolation used
549 // nice agreement in seeds with MC track parameters - problem in extrapoloation - to be fixed
550 // to check later
551 Double_t y1,y2,z1,z2;
552 trackParam->GetYAt(xyz1[0],bz,y1);
553 trackParam->GetZAt(xyz1[0],bz,z1);
554 trackParam->GetYAt(xyz2[0],bz,y2);
555 trackParam->GetZAt(xyz2[0],bz,z2);
556 if (TMath::Abs(y1-xyz1[1])> TMath::Sqrt(p1r.GetCov()[3]*5)){
557 AliWarningClass("Seeding problem y1\n");
558 }
559 if (TMath::Abs(y2-xyz2[1])> TMath::Sqrt(p2r.GetCov()[3]*5)){
560 AliWarningClass("Seeding problem y2\n");
561 }
562 if (TMath::Abs(z1-xyz1[2])> TMath::Sqrt(p1r.GetCov()[5]*5)){
563 AliWarningClass("Seeding problem z1\n");
564 }
565 }
566 return trackParam;
567}
568
569Double_t AliTrackerBase::FitTrack(AliExternalTrackParam * trackParam, AliTrackPointArray *pointArray, Double_t mass, Double_t maxStep){
570 //
571 // refit the track - trackParam using the points in point array
572 //
573 const Double_t kMaxSnp=0.99;
574 if (!trackParam) return 0;
575 Int_t npoints=pointArray->GetNPoints();
576 AliTrackPoint point,point2;
577 Double_t pointPos[2]={0,0};
578 Double_t pointCov[3]={0,0,0};
579 // choose coordinate frame
580 // in standard way the coordinate frame should be changed point by point
581 // Some problems with rotation observed
582 // rotate method of AliExternalTrackParam should be revisited
583 pointArray->GetPoint(point,0);
584 pointArray->GetPoint(point2,npoints-1);
585 Double_t alpha=TMath::ATan2(point.GetY()-point2.GetY(), point.GetX()-point2.GetX());
586
587 for (Int_t ipoint=npoints-1; ipoint>0; ipoint-=1){
588 pointArray->GetPoint(point,ipoint);
589 AliTrackPoint pr = point.Rotate(alpha);
590 trackParam->Rotate(alpha);
591 Bool_t status = PropagateTrackTo(trackParam,pr.GetX(),mass,maxStep,kFALSE,kMaxSnp);
592 if(!status){
593 AliWarningClass("Problem to propagate\n");
594 break;
595 }
596 if (TMath::Abs(trackParam->GetSnp())>kMaxSnp){
597 AliWarningClass("sin(phi) > kMaxSnp \n");
598 break;
599 }
600 pointPos[0]=pr.GetY();//local y
601 pointPos[1]=pr.GetZ();//local z
602 pointCov[0]=pr.GetCov()[3];//simay^2
603 pointCov[1]=pr.GetCov()[4];//sigmayz
604 pointCov[2]=pr.GetCov()[5];//sigmaz^2
605 trackParam->Update(pointPos,pointCov);
606 }
607 return 0;
608}
363db7c3 609
610
611
612void AliTrackerBase::UpdateTrack(AliExternalTrackParam &track1, const AliExternalTrackParam &track2){
613 //
614 // Update track 1 with track 2
615 //
616 //
617 //
618 TMatrixD vecXk(5,1); // X vector
619 TMatrixD covXk(5,5); // X covariance
620 TMatrixD matHk(5,5); // vector to mesurement
621 TMatrixD measR(5,5); // measurement error
622 TMatrixD vecZk(5,1); // measurement
623 //
624 TMatrixD vecYk(5,1); // Innovation or measurement residual
625 TMatrixD matHkT(5,5);
626 TMatrixD matSk(5,5); // Innovation (or residual) covariance
627 TMatrixD matKk(5,5); // Optimal Kalman gain
628 TMatrixD mat1(5,5); // update covariance matrix
629 TMatrixD covXk2(5,5); //
630 TMatrixD covOut(5,5);
631 //
632 Double_t *param1=(Double_t*) track1.GetParameter();
633 Double_t *covar1=(Double_t*) track1.GetCovariance();
634 Double_t *param2=(Double_t*) track2.GetParameter();
635 Double_t *covar2=(Double_t*) track2.GetCovariance();
636 //
637 // copy data to the matrix
638 for (Int_t ipar=0; ipar<5; ipar++){
639 for (Int_t jpar=0; jpar<5; jpar++){
640 covXk(ipar,jpar) = covar1[track1.GetIndex(ipar, jpar)];
641 measR(ipar,jpar) = covar2[track2.GetIndex(ipar, jpar)];
642 matHk(ipar,jpar)=0;
643 mat1(ipar,jpar)=0;
644 }
645 vecXk(ipar,0) = param1[ipar];
646 vecZk(ipar,0) = param2[ipar];
647 matHk(ipar,ipar)=1;
648 mat1(ipar,ipar)=1;
649 }
650 //
651 //
652 //
653 //
654 //
655 vecYk = vecZk-matHk*vecXk; // Innovation or measurement residual
656 matHkT=matHk.T(); matHk.T();
657 matSk = (matHk*(covXk*matHkT))+measR; // Innovation (or residual) covariance
658 matSk.Invert();
659 matKk = (covXk*matHkT)*matSk; // Optimal Kalman gain
660 vecXk += matKk*vecYk; // updated vector
661 covXk2 = (mat1-(matKk*matHk));
662 covOut = covXk2*covXk;
663 //
664 //
665 //
666 // copy from matrix to parameters
667 if (0) {
668 vecXk.Print();
669 vecZk.Print();
670 //
671 measR.Print();
672 covXk.Print();
673 covOut.Print();
674 //
675 track1.Print();
676 track2.Print();
677 }
678
679 for (Int_t ipar=0; ipar<5; ipar++){
680 param1[ipar]= vecXk(ipar,0) ;
681 for (Int_t jpar=0; jpar<5; jpar++){
682 covar1[track1.GetIndex(ipar, jpar)]=covOut(ipar,jpar);
683 }
684 }
685}
686
687