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 //-------------------------------------------------------------------------
17 // Implementation of the ITS track class
19 // Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
20 // dEdx analysis by: Boris Batyunya, JINR, Boris.Batiounia@cern.ch
21 //-------------------------------------------------------------------------
24 #include "AliCluster.h"
25 #include "AliESDtrack.h"
26 #include "AliITStrackV2.h"
28 ClassImp(AliITStrackV2)
32 //____________________________________________________________________________
33 AliITStrackV2::AliITStrackV2():AliKalmanTrack(),
59 for(Int_t i=0; i<kMaxLayer; i++) fIndex[i]=0;
60 for(Int_t i=0; i<4; i++) fdEdxSample[i]=0;
64 //____________________________________________________________________________
65 AliITStrackV2::AliITStrackV2(AliESDtrack& t,Bool_t c) throw (const Char_t *) :
67 //------------------------------------------------------------------
68 // Conversion ESD track -> ITS track.
69 // If c==kTRUE, create the ITS track out of the constrained params.
70 //------------------------------------------------------------------
71 SetNumberOfClusters(t.GetITSclusters(fIndex));
72 SetLabel(t.GetLabel());
77 fdEdx=t.GetITSsignal();
78 fAlpha = t.GetAlpha();
79 if (fAlpha < -TMath::Pi()) fAlpha += 2*TMath::Pi();
80 else if (fAlpha >= TMath::Pi()) fAlpha -= 2*TMath::Pi();
82 //Conversion of the track parameters
84 if (c) t.GetConstrainedExternalParameters(x,p);
85 else t.GetExternalParameters(x,p);
86 fX=x; x=GetConvConst();
93 //Conversion of the covariance matrix
95 if (c) t.GetConstrainedExternalCovariance(cv);
96 else t.GetExternalCovariance(cv);
98 fC10=cv[1 ]; fC11=cv[2 ];
99 fC20=cv[3 ]; fC21=cv[4 ]; fC22=cv[5 ];
100 fC30=cv[6 ]; fC31=cv[7 ]; fC32=cv[8 ]; fC33=cv[9 ];
101 fC40=cv[10]/x; fC41=cv[11]/x; fC42=cv[12]/x; fC43=cv[13]/x; fC44=cv[14]/x/x;
103 if (t.GetStatus()&AliESDtrack::kTIME) {
105 Double_t times[10]; t.GetIntegratedTimes(times); SetIntegratedTimes(times);
106 SetIntegratedLength(t.GetIntegratedLength());
110 if (!Invariant()) throw "AliITStrackV2: conversion failed !\n";
113 void AliITStrackV2::UpdateESDtrack(ULong_t flags) const {
114 fESDtrack->UpdateTrackParams(this,flags);
116 void AliITStrackV2::SetConstrainedESDtrack(Double_t chi2) const {
117 fESDtrack->SetConstrainedTrackParams(this,chi2);
120 //____________________________________________________________________________
121 AliITStrackV2::AliITStrackV2(const AliITStrackV2& t) : AliKalmanTrack(t) {
122 //------------------------------------------------------------------
124 //------------------------------------------------------------------
129 fP0=t.fP0; fP1=t.fP1; fP2=t.fP2; fP3=t.fP3; fP4=t.fP4;
132 fC10=t.fC10; fC11=t.fC11;
133 fC20=t.fC20; fC21=t.fC21; fC22=t.fC22;
134 fC30=t.fC30; fC31=t.fC31; fC32=t.fC32; fC33=t.fC33;
135 fC40=t.fC40; fC41=t.fC41; fC42=t.fC42; fC43=t.fC43; fC44=t.fC44;
137 Int_t n=GetNumberOfClusters();
138 for (Int_t i=0; i<n; i++) {
139 fIndex[i]=t.fIndex[i];
140 if (i<4) fdEdxSample[i]=t.fdEdxSample[i];
142 fESDtrack=t.fESDtrack;
145 //_____________________________________________________________________________
146 Int_t AliITStrackV2::Compare(const TObject *o) const {
147 //-----------------------------------------------------------------
148 // This function compares tracks according to the their curvature
149 //-----------------------------------------------------------------
150 AliITStrackV2 *t=(AliITStrackV2*)o;
151 //Double_t co=TMath::Abs(t->Get1Pt());
152 //Double_t c =TMath::Abs(Get1Pt());
153 Double_t co=t->GetSigmaY2()*t->GetSigmaZ2();
154 Double_t c =GetSigmaY2()*GetSigmaZ2();
156 else if (c<co) return -1;
160 //_____________________________________________________________________________
161 void AliITStrackV2::GetExternalCovariance(Double_t cc[15]) const {
162 //-------------------------------------------------------------------------
163 // This function returns an external representation of the covriance matrix.
164 // (See comments in AliTPCtrack.h about external track representation)
165 //-------------------------------------------------------------------------
166 Double_t a=GetConvConst();
169 cc[1 ]=fC10; cc[2 ]=fC11;
170 cc[3 ]=fC20; cc[4 ]=fC21; cc[5 ]=fC22;
171 cc[6 ]=fC30; cc[7 ]=fC31; cc[8 ]=fC32; cc[9 ]=fC33;
172 cc[10]=fC40*a; cc[11]=fC41*a; cc[12]=fC42*a; cc[13]=fC43*a; cc[14]=fC44*a*a;
175 //____________________________________________________________________________
176 Int_t AliITStrackV2::PropagateToVertex(Double_t d,Double_t x0) {
177 //------------------------------------------------------------------
178 //This function propagates a track to the minimal distance from the origin
179 //------------------------------------------------------------------
180 //Double_t xv=fP2*(fX*fP2 - fP0*TMath::Sqrt(1.- fP2*fP2)); //linear approxim.
181 Double_t tgf=-(fP4*fX - fP2)/(fP4*fP0 + TMath::Sqrt(1 - fP2*fP2));
182 Double_t snf=tgf/TMath::Sqrt(1.+ tgf*tgf);
183 Double_t xv=(snf - fP2)/fP4 + fX;
184 return PropagateTo(xv,d,x0);
187 //____________________________________________________________________________
188 Int_t AliITStrackV2::
189 GetGlobalXYZat(Double_t xk, Double_t &x, Double_t &y, Double_t &z) const {
190 //------------------------------------------------------------------
191 //This function returns a track position in the global system
192 //------------------------------------------------------------------
194 Double_t f1=fP2, f2=f1 + fP4*dx;
195 if (TMath::Abs(f2) >= 0.9999) {
196 Int_t n=GetNumberOfClusters();
198 Warning("GetGlobalXYZat","Propagation failed (%d) !\n",n);
202 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
204 Double_t yk = fP0 + dx*(f1+f2)/(r1+r2);
205 Double_t zk = fP1 + dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
207 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
215 //_____________________________________________________________________________
216 Double_t AliITStrackV2::GetPredictedChi2(const AliCluster *c) const
218 //-----------------------------------------------------------------
219 // This function calculates a predicted chi2 increment.
220 //-----------------------------------------------------------------
221 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
222 r00+=fC00; r01+=fC10; r11+=fC11;
224 Double_t det=r00*r11 - r01*r01;
225 if (TMath::Abs(det) < 1.e-30) {
226 Int_t n=GetNumberOfClusters();
228 Warning("GetPredictedChi2","Singular matrix (%d) !\n",n);
231 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
233 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
235 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
238 //____________________________________________________________________________
239 Int_t AliITStrackV2::CorrectForMaterial(Double_t d, Double_t x0) {
240 //------------------------------------------------------------------
241 //This function corrects the track parameters for crossed material
242 //------------------------------------------------------------------
243 Double_t p2=(1.+ fP3*fP3)/(Get1Pt()*Get1Pt());
244 Double_t beta2=p2/(p2 + GetMass()*GetMass());
245 d*=TMath::Sqrt((1.+ fP3*fP3)/(1.- fP2*fP2));
247 //Multiple scattering******************
249 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(d);
250 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*TMath::Abs(d)*9.36*2.33;
251 fC22 += theta2*(1.- fP2*fP2)*(1. + fP3*fP3);
252 fC33 += theta2*(1. + fP3*fP3)*(1. + fP3*fP3);
253 fC43 += theta2*fP3*fP4*(1. + fP3*fP3);
254 fC44 += theta2*fP3*fP4*fP3*fP4;
257 //Energy losses************************
260 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d;
261 if (beta2/(1-beta2)>3.5*3.5)
262 dE=0.153e-3/beta2*(log(3.5*5940)+0.5*log(beta2/(1-beta2)) - beta2)*d;
264 fP4*=(1.- TMath::Sqrt(p2+GetMass()*GetMass())/p2*dE);
267 if (!Invariant()) return 0;
272 //____________________________________________________________________________
273 Int_t AliITStrackV2::PropagateTo(Double_t xk, Double_t d, Double_t x0) {
274 //------------------------------------------------------------------
275 //This function propagates a track
276 //------------------------------------------------------------------
277 Double_t x1=fX, x2=xk, dx=x2-x1;
278 Double_t f1=fP2, f2=f1 + fP4*dx;
279 if (TMath::Abs(f2) >= 0.9999) {
280 Int_t n=GetNumberOfClusters();
282 Warning("PropagateTo","Propagation failed !\n",n);
286 // old position [SR, GSI, 17.02.2003]
287 Double_t oldX = fX, oldY = fP0, oldZ = fP1;
289 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
291 fP0 += dx*(f1+f2)/(r1+r2);
292 fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
297 Double_t f02= dx/(r1*r1*r1);
298 Double_t f04=0.5*dx*dx/(r1*r1*r1);
299 Double_t f12= dx*fP3*f1/(r1*r1*r1);
300 Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1);
305 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
306 Double_t b02=f24*fC40;
307 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
308 Double_t b12=f24*fC41;
309 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
310 Double_t b22=f24*fC42;
311 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
312 Double_t b42=f24*fC44;
313 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
314 Double_t b32=f24*fC43;
317 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42;
318 Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32;
319 Double_t a22=f24*b42;
321 //F*C*Ft = C + (b + bt + a)
322 fC00 += b00 + b00 + a00;
323 fC10 += b10 + b01 + a01;
324 fC20 += b20 + b02 + a02;
327 fC11 += b11 + b11 + a11;
328 fC21 += b21 + b12 + a12;
331 fC22 += b22 + b22 + a22;
337 if (!CorrectForMaterial(d,x0)) return 0;
339 // Integrated Time [SR, GSI, 17.02.2003]
340 if (IsStartedTimeIntegral() && fX>oldX) {
341 Double_t l2 = (fX-oldX)*(fX-oldX)+(fP0-oldY)*(fP0-oldY)+
342 (fP1-oldZ)*(fP1-oldZ);
343 AddTimeStep(TMath::Sqrt(l2));
350 //____________________________________________________________________________
351 Int_t AliITStrackV2::Update(const AliCluster* c, Double_t chi2, UInt_t index) {
352 //------------------------------------------------------------------
353 //This function updates track parameters
354 //------------------------------------------------------------------
355 Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
357 Double_t c10=fC10, c11=fC11;
358 Double_t c20=fC20, c21=fC21, c22=fC22;
359 Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
360 Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
363 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
364 r00+=fC00; r01+=fC10; r11+=fC11;
365 Double_t det=r00*r11 - r01*r01;
366 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
369 Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
370 Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
371 Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
372 Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
373 Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
375 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
376 Double_t sf=fP2 + k20*dy + k21*dz;
378 fP0 += k00*dy + k01*dz;
379 fP1 += k10*dy + k11*dz;
381 fP3 += k30*dy + k31*dz;
382 fP4 += k40*dy + k41*dz;
384 Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40;
385 Double_t c12=fC21, c13=fC31, c14=fC41;
387 fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11;
388 fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13;
389 fC40-=k00*c04+k01*c14;
391 fC11-=k10*c01+k11*fC11;
392 fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13;
393 fC41-=k10*c04+k11*c14;
395 fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13;
396 fC42-=k20*c04+k21*c14;
398 fC33-=k30*c03+k31*c13;
399 fC43-=k30*c04+k31*c14;
401 fC44-=k40*c04+k41*c14;
404 fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
407 fC20=c20; fC21=c21; fC22=c22;
408 fC30=c30; fC31=c31; fC32=c32; fC33=c33;
409 fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
413 if (chi2<0) return 1;
415 Int_t n=GetNumberOfClusters();
417 SetNumberOfClusters(n+1);
418 SetChi2(GetChi2()+chi2);
423 Int_t AliITStrackV2::Invariant() const {
424 //------------------------------------------------------------------
425 // This function is for debugging purpose only
426 //------------------------------------------------------------------
427 Int_t n=GetNumberOfClusters();
429 if (TMath::Abs(fP2)>=0.9999){
430 if (n>kWARN) Warning("Invariant","fP2=%f\n",fP2);
433 if (fC00<=0 || fC00>9.) {
434 if (n>kWARN) Warning("Invariant","fC00=%f\n",fC00);
437 if (fC11<=0 || fC11>9.) {
438 if (n>kWARN) Warning("Invariant","fC11=%f\n",fC11);
441 if (fC22<=0 || fC22>1.) {
442 if (n>kWARN) Warning("Invariant","fC22=%f\n",fC22);
445 if (fC33<=0 || fC33>1.) {
446 if (n>kWARN) Warning("Invariant","fC33=%f\n",fC33);
449 if (fC44<=0 || fC44>6e-5) {
450 if (n>kWARN) Warning("Invariant","fC44=%f\n",fC44);
456 //____________________________________________________________________________
457 Int_t AliITStrackV2::Propagate(Double_t alp,Double_t xk) {
458 //------------------------------------------------------------------
459 //This function propagates a track
460 //------------------------------------------------------------------
461 Double_t alpha=fAlpha, x=fX;
462 Double_t p0=fP0,p1=fP1,p2=fP2,p3=fP3,p4=fP4;
464 Double_t c10=fC10, c11=fC11;
465 Double_t c20=fC20, c21=fC21, c22=fC22;
466 Double_t c30=fC30, c31=fC31, c32=fC32, c33=fC33;
467 Double_t c40=fC40, c41=fC41, c42=fC42, c43=fC43, c44=fC44;
469 if (alp < -TMath::Pi()) alp += 2*TMath::Pi();
470 else if (alp >= TMath::Pi()) alp -= 2*TMath::Pi();
471 Double_t ca=TMath::Cos(alp-fAlpha), sa=TMath::Sin(alp-fAlpha);
472 Double_t sf=fP2, cf=TMath::Sqrt(1.- fP2*fP2);
474 // **** rotation **********************
481 Double_t rr=(ca+sf/cf*sa);
501 // **** translation ******************
504 Double_t f1=fP2, f2=f1 + fP4*dx;
505 if (TMath::Abs(f2) >= 0.9999) {
506 Int_t n=GetNumberOfClusters();
508 Warning("Propagate","Propagation failed (%d) !\n",n);
511 Double_t r1=TMath::Sqrt(1.- f1*f1), r2=TMath::Sqrt(1.- f2*f2);
514 fP0 += dx*(f1+f2)/(r1+r2);
515 fP1 += dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
520 Double_t f02= dx/(r1*r1*r1);
521 Double_t f04=0.5*dx*dx/(r1*r1*r1);
522 Double_t f12= dx*fP3*f1/(r1*r1*r1);
523 Double_t f14=0.5*dx*dx*fP3*f1/(r1*r1*r1);
528 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
529 Double_t b02=f24*fC40;
530 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
531 Double_t b12=f24*fC41;
532 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
533 Double_t b22=f24*fC42;
534 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
535 Double_t b42=f24*fC44;
536 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
537 Double_t b32=f24*fC43;
540 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a02=f02*b22+f04*b42;
541 Double_t a11=f12*b21+f14*b41+f13*b31,a12=f12*b22+f14*b42+f13*b32;
542 Double_t a22=f24*b42;
544 //F*C*Ft = C + (b + bt + a)
545 fC00 += b00 + b00 + a00;
546 fC10 += b10 + b01 + a01;
547 fC20 += b20 + b02 + a02;
550 fC11 += b11 + b11 + a11;
551 fC21 += b21 + b12 + a12;
554 fC22 += b22 + b22 + a22;
561 fP0=p0; fP1=p1; fP2=p2; fP3=p3; fP4=p4;
564 fC20=c20; fC21=c21; fC22=c22;
565 fC30=c30; fC31=c31; fC32=c32; fC33=c33;
566 fC40=c40; fC41=c41; fC42=c42; fC43=c43; fC44=c44;
575 Double_t AliITStrackV2::GetD(Double_t x, Double_t y) const {
576 //------------------------------------------------------------------
577 // This function calculates the transverse impact parameter
578 // with respect to a point with global coordinates (x,y)
579 //------------------------------------------------------------------
580 Double_t xt=fX, yt=fP0;
582 Double_t sn=TMath::Sin(fAlpha), cs=TMath::Cos(fAlpha);
583 Double_t a = x*cs + y*sn;
584 y = -x*sn + y*cs; x=a;
587 sn=fP4*xt - fP2; cs=fP4*yt + TMath::Sqrt(1.- fP2*fP2);
588 a=2*(xt*fP2 - yt*TMath::Sqrt(1.- fP2*fP2))-fP4*(xt*xt + yt*yt);
590 return a/(1 + TMath::Sqrt(sn*sn + cs*cs));
593 Double_t AliITStrackV2::GetZat(Double_t x) const {
594 //------------------------------------------------------------------
595 // This function calculates the z at given x point - in current coordinate system
596 //------------------------------------------------------------------
597 Double_t x1=fX, x2=x, dx=x2-x1;
599 Double_t f1=fP2, f2=f1 + fP4*dx;
600 if (TMath::Abs(f2) >= 0.9999) {
603 Double_t r1=sqrt(1.- f1*f1), r2=sqrt(1.- f2*f2);
604 Double_t z = fP1 + dx*(f1+f2)/(f1*r2 + f2*r1)*fP3;
611 Int_t AliITStrackV2::Improve(Double_t x0,Double_t xyz[3],Double_t ers[3]) {
612 //------------------------------------------------------------------
613 //This function improves angular track parameters
614 //------------------------------------------------------------------
615 Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
616 //Double_t xv = xyz[0]*cs + xyz[1]*sn; // vertex
617 Double_t yv =-xyz[0]*sn + xyz[1]*cs; // in the
618 Double_t zv = xyz[2]; // local frame
619 Double_t dy=fP0-yv, dz=fP1-zv;
620 Double_t r2=fX*fX+dy*dy;
621 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
622 Double_t beta2=p2/(p2 + GetMass()*GetMass());
623 x0*=TMath::Sqrt((1.+ GetTgl()*GetTgl())/(1.- GetSnp()*GetSnp()));
624 Double_t theta2=14.1*14.1/(beta2*p2*1e6)*x0;
625 //Double_t theta2=1.0259e-6*14*14/28/(beta2*p2)*x0*9.36*2.33;
627 Double_t parp=0.5*(fP4*fX + dy*TMath::Sqrt(4/r2-fP4*fP4));
628 Double_t sigma2p = theta2*(1.- GetSnp()*GetSnp())*(1. + GetTgl()*GetTgl());
629 sigma2p += fC00/r2*(1.- dy*dy/r2)*(1.- dy*dy/r2);
630 sigma2p += ers[1]*ers[1]/r2;
631 sigma2p += 0.25*fC44*fX*fX;
632 Double_t eps2p=sigma2p/(fC22+sigma2p);
633 fP0 += fC20/(fC22+sigma2p)*(parp-fP2);
634 fP2 = eps2p*fP2 + (1-eps2p)*parp;
639 Double_t parl=0.5*fP4*dz/TMath::ASin(0.5*fP4*TMath::Sqrt(r2));
640 Double_t sigma2l=theta2;
641 sigma2l += fC11/r2+fC00*dy*dy*dz*dz/(r2*r2*r2);
642 sigma2l += ers[2]*ers[2]/r2;
643 Double_t eps2l=sigma2l/(fC33+sigma2l);
644 fP1 += fC31/(fC33+sigma2l)*(parl-fP3);
645 fP4 += fC43/(fC33+sigma2l)*(parl-fP3);
646 fP3 = eps2l*fP3 + (1-eps2l)*parl;
647 fC33 *= eps2l; fC43 *= eps2l;
650 if (!Invariant()) return 0;
654 void AliITStrackV2::ResetCovariance() {
655 //------------------------------------------------------------------
656 //This function makes a track forget its history :)
657 //------------------------------------------------------------------
661 fC20=0.; fC21=0.; fC22*=10.;
662 fC30=0.; fC31=0.; fC32=0.; fC33*=10.;
663 fC40=0.; fC41=0.; fC42=0.; fC43=0.; fC44*=10.;
667 void AliITStrackV2::CookdEdx(Double_t low, Double_t up) {
668 //-----------------------------------------------------------------
669 // This function calculates dE/dX within the "low" and "up" cuts.
670 // Origin: Boris Batyunya, JINR, Boris.Batiounia@cern.ch
671 //-----------------------------------------------------------------
672 // The clusters order is: SSD-2, SSD-1, SDD-2, SDD-1, SPD-2, SPD-1
676 for (i=0; i<GetNumberOfClusters(); i++) {
677 Int_t idx=GetClusterIndex(i);
678 idx=(idx&0xf0000000)>>28;
679 if (idx>1) nc++; // Take only SSD and SDD
682 Int_t swap;//stupid sorting
685 for (i=0; i<nc-1; i++) {
686 if (fdEdxSample[i]<=fdEdxSample[i+1]) continue;
687 Float_t tmp=fdEdxSample[i];
688 fdEdxSample[i]=fdEdxSample[i+1]; fdEdxSample[i+1]=tmp;
693 Int_t nl=Int_t(low*nc), nu=Int_t(up*nc); //b.b. to take two lowest dEdX
694 // values from four ones choose
697 for (i=nl; i<nu; i++) dedx += fdEdxSample[i];
698 if (nu-nl>0) dedx /= (nu-nl);