1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
16 /* $Id: AliTrackerBase.cxx 38069 2009-12-24 16:56:18Z belikov $ */
18 //-------------------------------------------------------------------------
19 // Implementation of the AliTrackerBase class
20 // that is the base for the AliTracker class
21 // Origin: Marian.Ivanov@cern.ch
22 //-------------------------------------------------------------------------
25 #include <TGeoManager.h>
28 #include "AliTrackerBase.h"
29 #include "AliExternalTrackParam.h"
30 #include "AliTrackPointArray.h"
33 extern TGeoManager *gGeoManager;
35 ClassImp(AliTrackerBase)
37 AliTrackerBase::AliTrackerBase():
46 //--------------------------------------------------------------------
47 // The default constructor.
48 //--------------------------------------------------------------------
49 if (!TGeoGlobalMagField::Instance()->GetField())
50 AliWarning("Field map is not set.");
53 //__________________________________________________________________________
54 AliTrackerBase::AliTrackerBase(const AliTrackerBase &atr):
63 //--------------------------------------------------------------------
64 // The default constructor.
65 //--------------------------------------------------------------------
66 if (!TGeoGlobalMagField::Instance()->GetField())
67 AliWarning("Field map is not set.");
70 //__________________________________________________________________________
71 Double_t AliTrackerBase::GetBz()
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;
79 //__________________________________________________________________________
80 Double_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;
90 //__________________________________________________________________________
91 void 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();
98 b[2] = 0.5*kAlmost0Field;
102 if (fld->IsUniform()) {
104 b[2] = fld->SolenoidField();
108 b[2] = (TMath::Sign(0.5*kAlmost0Field,b[2]) + b[2]);
112 Double_t AliTrackerBase::MeanMaterialBudget(const Double_t *start, const Double_t *end, Double_t *mparam)
115 // Calculate mean material budget and material properties between
116 // the points "start" and "end".
118 // "mparam" - parameters used for the energy and multiple scattering
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
129 // Origin: Marian Ivanov, Marian.Ivanov@cern.ch
131 // Corrections and improvements by
132 // Andrea Dainese, Andrea.Dainese@lnl.infn.it,
133 // Andrei Gheata, Andrei.Gheata@cern.ch
136 mparam[0]=0; mparam[1]=1; mparam[2] =0; mparam[3] =0;
137 mparam[4]=0; mparam[5]=0; mparam[6]=0;
139 Double_t bparam[6]; // total parameters
140 Double_t lparam[6]; // local parameters
142 for (Int_t i=0;i<6;i++) bparam[i]=0;
145 AliErrorClass("No TGeo\n");
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]));
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;
161 // Initialize start point and direction
162 TGeoNode *currentnode = 0;
163 TGeoNode *startnode = gGeoManager->InitTrack(start, dir);
165 AliErrorClass(Form("start point out of geometry: x %f, y %f, z %f",
166 start[0],start[1],start[2]));
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();
175 lparam[5] = lparam[3]/lparam[2];
176 if (material->IsMixture()) {
177 TGeoMixture * mixture = (TGeoMixture*)material;
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];
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];
201 // Try to cross the boundary and see what is next
203 while (length>TGeoShape::Tolerance()) {
204 currentnode = gGeoManager->GetCurrentNode();
205 if (snext<2.*TGeoShape::Tolerance()) nzero++;
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;
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;
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];
229 if (snext>=length) break;
230 if (!currentnode) break;
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;
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];
248 gGeoManager->FindNextBoundaryAndStep(length, kFALSE);
249 snext = gGeoManager->GetStep();
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;
261 AliTrackerBase::PropagateTrackTo(AliExternalTrackParam *track, Double_t xToGo,
262 Double_t mass, Double_t maxStep, Bool_t rotateTo, Double_t maxSnp, Double_t sign){
263 //----------------------------------------------------------------
265 // Propagates the track to the plane X=xk (cm) using the magnetic field map
266 // and correcting for the crossed material.
268 // mass - mass used in propagation - used for energy loss correction
269 // maxStep - maximal step for propagation
271 // Origin: Marian Ivanov, Marian.Ivanov@cern.ch
273 //----------------------------------------------------------------
274 const Double_t kEpsilon = 0.00001;
275 Double_t xpos = track->GetX();
276 Double_t dir = (xpos<xToGo) ? 1.:-1.;
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
284 Double_t bz=GetBz(xyz0); // getting the local Bz
286 if (!track->GetXYZAt(x,bz,xyz1)) return kFALSE; // no prolongation
287 xyz1[2]+=kEpsilon; // waiting for bug correction in geo
289 if (TMath::Abs(track->GetSnpAt(x,bz)) >= maxSnp) return kFALSE;
290 if (!track->PropagateTo(x,bz)) return kFALSE;
292 MeanMaterialBudget(xyz0,xyz1,param);
293 Double_t xrho=param[0]*param[4]*sign, xx0=param[1];
295 if (!track->CorrectForMeanMaterial(xx0,xrho,mass)) return kFALSE;
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]);
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;
308 xpos = track->GetX();
314 AliTrackerBase::PropagateTrackToBxByBz(AliExternalTrackParam *track,
316 Double_t mass, Double_t maxStep, Bool_t rotateTo, Double_t maxSnp,Double_t sign){
317 //----------------------------------------------------------------
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.
323 // mass - mass used in propagation - used for energy loss correction
324 // maxStep - maximal step for propagation
326 // Origin: Marian Ivanov, Marian.Ivanov@cern.ch
328 //----------------------------------------------------------------
329 const Double_t kEpsilon = 0.00001;
330 Double_t xpos = track->GetX();
331 Double_t dir = (xpos<xToGo) ? 1.:-1.;
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
339 Double_t b[3]; GetBxByBz(xyz0,b); // getting the local Bx, By and Bz
341 if (!track->GetXYZAt(x,b[2],xyz1)) return kFALSE; // no prolongation
342 xyz1[2]+=kEpsilon; // waiting for bug correction in geo
344 if (TMath::Abs(track->GetSnpAt(x,b[2])) >= maxSnp) return kFALSE;
345 if (!track->PropagateToBxByBz(x,b)) return kFALSE;
347 MeanMaterialBudget(xyz0,xyz1,param);
348 Double_t xrho=param[0]*param[4]*sign, xx0=param[1];
350 if (!track->CorrectForMeanMaterial(xx0,xrho,mass)) return kFALSE;
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]);
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;
363 xpos = track->GetX();
368 Double_t AliTrackerBase::GetTrackPredictedChi2(AliExternalTrackParam *track,
369 Double_t mass, Double_t step,
370 const AliExternalTrackParam *backup) {
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
377 Double_t chi2=kVeryBig;
378 Double_t alpha=backup->GetAlpha();
379 if (!track->Rotate(alpha)) return chi2;
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;
385 chi2=track->GetPredictedChi2(backup);
393 Double_t AliTrackerBase::MakeC(Double_t x1,Double_t y1,
394 Double_t x2,Double_t y2,
395 Double_t x3,Double_t y3)
397 //-----------------------------------------------------------------
398 // Initial approximation of the track curvature
399 //-----------------------------------------------------------------
405 Double_t det = x3*y2-x2*y3;
406 if (TMath::Abs(det)<1e-10) {
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);
418 Double_t AliTrackerBase::MakeSnp(Double_t x1,Double_t y1,
419 Double_t x2,Double_t y2,
420 Double_t x3,Double_t y3)
422 //-----------------------------------------------------------------
423 // Initial approximation of the track snp
424 //-----------------------------------------------------------------
430 Double_t det = x3*y2-x2*y3;
431 if (TMath::Abs(det)<1e-10) {
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);
441 if (y2*x2<0.) x0*=-1;
445 Double_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)
449 //-----------------------------------------------------------------
450 // Initial approximation of the tangent of the track dip angle
451 //-----------------------------------------------------------------
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.));
464 Double_t AliTrackerBase::MakeTgl(Double_t x1,Double_t y1,
465 Double_t x2,Double_t y2,
466 Double_t z1,Double_t z2)
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));
475 AliExternalTrackParam * AliTrackerBase::MakeSeed( AliTrackPoint &point0, AliTrackPoint &point1, AliTrackPoint &point2){
477 // Make Seed - AliExternalTrackParam from input 3 points
478 // returning seed in local frame of point0
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];
488 // get points in frame of point 0
490 AliTrackPoint p0r = point0.Rotate(alpha);
491 AliTrackPoint p1r = point1.Rotate(alpha);
492 AliTrackPoint p2r = point2.Rotate(alpha);
503 // make covariance estimate
506 Double_t param[5]={0,0,0,0,0};
507 for (Int_t m=0; m<15; m++) covar[m]=0;
509 // calculate intitial param
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]);
516 //covariance matrix - only diagonal elements
517 //Double_t dist=p0r.GetX()-p2r.GetX();
519 covar[0]= p0r.GetCov()[3];
520 covar[2]= p0r.GetCov()[5];
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;
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;
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;
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);
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
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");
559 if (TMath::Abs(y2-xyz2[1])> TMath::Sqrt(p2r.GetCov()[3]*5)){
560 AliWarningClass("Seeding problem y2\n");
562 if (TMath::Abs(z1-xyz1[2])> TMath::Sqrt(p1r.GetCov()[5]*5)){
563 AliWarningClass("Seeding problem z1\n");
569 Double_t AliTrackerBase::FitTrack(AliExternalTrackParam * trackParam, AliTrackPointArray *pointArray, Double_t mass, Double_t maxStep){
571 // refit the track - trackParam using the points in point array
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());
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);
593 AliWarningClass("Problem to propagate\n");
596 if (TMath::Abs(trackParam->GetSnp())>kMaxSnp){
597 AliWarningClass("sin(phi) > kMaxSnp \n");
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);
612 void AliTrackerBase::UpdateTrack(AliExternalTrackParam &track1, const AliExternalTrackParam &track2){
614 // Update track 1 with track 2
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
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);
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();
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)];
645 vecXk(ipar,0) = param1[ipar];
646 vecZk(ipar,0) = param2[ipar];
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
659 matKk = (covXk*matHkT)*matSk; // Optimal Kalman gain
660 vecXk += matKk*vecYk; // updated vector
661 covXk2 = (mat1-(matKk*matHk));
662 covOut = covXk2*covXk;
666 // copy from matrix to parameters
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);