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[u/mrichter/AliRoot.git] / TPC / AliTPCtrack.cxx
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73042f01 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
803d1ab0 16/* $Id$ */
0938c7d3 17
73042f01 18//-----------------------------------------------------------------
19// Implementation of the TPC track class
7c27857f 20// This class is used by the AliTPCtracker class
21// Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
73042f01 22//-----------------------------------------------------------------
23
19364939 24#include <Riostream.h>
b19a0509 25
73042f01 26#include "AliTPCtrack.h"
7c27857f 27#include "AliCluster.h"
9c9d2487 28#include "AliBarrelTrack.h"
83d73500 29#include "AliESDtrack.h"
73042f01 30
31ClassImp(AliTPCtrack)
b9de75e1 32
e3f7105e 33//_________________________________________________________________________
34AliTPCtrack::AliTPCtrack(): AliKalmanTrack()
35{
36 fX = fP0 = fP1 = fP2 = fP3 = fP3 = fP4 = 0.0;
37 fAlpha = fdEdx = 0.0;
9c9d2487 38 fNWrong = fNRotation = fNumber = 0; // [SR, 01.04.2003]
e3f7105e 39}
40
73042f01 41//_________________________________________________________________________
42AliTPCtrack::AliTPCtrack(UInt_t index, const Double_t xx[5],
b19a0509 43const Double_t cc[15], Double_t xref, Double_t alpha) : AliKalmanTrack() {
73042f01 44 //-----------------------------------------------------------------
45 // This is the main track constructor.
46 //-----------------------------------------------------------------
73042f01 47 fX=xref;
be9c5115 48 fAlpha=alpha;
49 if (fAlpha<-TMath::Pi()) fAlpha += 2*TMath::Pi();
50 if (fAlpha>=TMath::Pi()) fAlpha -= 2*TMath::Pi();
51 fdEdx=0.;
73042f01 52
b19a0509 53 fP0=xx[0]; fP1=xx[1]; fP2=xx[2]; fP3=xx[3]; fP4=xx[4];
73042f01 54
b19a0509 55 fC00=cc[0];
56 fC10=cc[1]; fC11=cc[2];
57 fC20=cc[3]; fC21=cc[4]; fC22=cc[5];
58 fC30=cc[6]; fC31=cc[7]; fC32=cc[8]; fC33=cc[9];
59 fC40=cc[10]; fC41=cc[11]; fC42=cc[12]; fC43=cc[13]; fC44=cc[14];
73042f01 60
be9c5115 61 fIndex[0]=index;
62 SetNumberOfClusters(1);
b9de75e1 63
64}
65
66//_____________________________________________________________________________
e1a65e92 67AliTPCtrack::AliTPCtrack(const AliKalmanTrack& t,Double_t alpha) :
68AliKalmanTrack(t) {
b9de75e1 69 //-----------------------------------------------------------------
70 // Conversion AliKalmanTrack -> AliTPCtrack.
71 //-----------------------------------------------------------------
b9de75e1 72 SetChi2(0.);
73 SetNumberOfClusters(0);
b9de75e1 74
75 fdEdx = 0.;
76 fAlpha = alpha;
77 if (fAlpha < -TMath::Pi()) fAlpha += 2*TMath::Pi();
78 else if (fAlpha >= TMath::Pi()) fAlpha -= 2*TMath::Pi();
79
80 //Conversion of the track parameters
81 Double_t x,p[5]; t.GetExternalParameters(x,p);
82 fX=x; x=GetConvConst();
83 fP0=p[0];
84 fP1=p[1];
85 fP3=p[3];
86 fP4=p[4]/x;
87 fP2=fP4*fX - p[2];
88
89 //Conversion of the covariance matrix
90 Double_t c[15]; t.GetExternalCovariance(c);
91 c[10]/=x; c[11]/=x; c[12]/=x; c[13]/=x; c[14]/=x*x;
92
93 Double_t c22=fX*fX*c[14] - 2*fX*c[12] + c[5];
94 Double_t c32=fX*c[13] - c[8];
95 Double_t c20=fX*c[10] - c[3], c21=fX*c[11] - c[4], c42=fX*c[14] - c[12];
96
97 fC00=c[0 ];
98 fC10=c[1 ]; fC11=c[2 ];
99 fC20=c20; fC21=c21; fC22=c22;
100 fC30=c[6 ]; fC31=c[7 ]; fC32=c32; fC33=c[9 ];
101 fC40=c[10]; fC41=c[11]; fC42=c42; fC43=c[13]; fC44=c[14];
102
73042f01 103}
104
83d73500 105//_____________________________________________________________________________
106AliTPCtrack::AliTPCtrack(const AliESDtrack& t) : AliKalmanTrack() {
107 //-----------------------------------------------------------------
108 // Conversion AliESDtrack -> AliTPCtrack.
109 //-----------------------------------------------------------------
110 SetNumberOfClusters(t.GetTPCclusters(fIndex));
111 SetLabel(t.GetLabel());
112 SetMass(t.GetMass());
113
114 fdEdx = t.GetTPCsignal();
115 fAlpha = t.GetAlpha();
116 if (fAlpha < -TMath::Pi()) fAlpha += 2*TMath::Pi();
117 else if (fAlpha >= TMath::Pi()) fAlpha -= 2*TMath::Pi();
118
119 //Conversion of the track parameters
120 Double_t x,p[5]; t.GetExternalParameters(x,p);
121 fX=x; x=GetConvConst();
122 fP0=p[0];
123 fP1=p[1];
124 fP3=p[3];
125 fP4=p[4]/x;
126 fP2=fP4*fX - p[2];
127
128 //Conversion of the covariance matrix
129 Double_t c[15]; t.GetExternalCovariance(c);
130 c[10]/=x; c[11]/=x; c[12]/=x; c[13]/=x; c[14]/=x*x;
131
132 Double_t c22=fX*fX*c[14] - 2*fX*c[12] + c[5];
133 Double_t c32=fX*c[13] - c[8];
134 Double_t c20=fX*c[10] - c[3], c21=fX*c[11] - c[4], c42=fX*c[14] - c[12];
135
136 fC00=c[0 ];
137 fC10=c[1 ]; fC11=c[2 ];
138 fC20=c20; fC21=c21; fC22=c22;
139 fC30=c[6 ]; fC31=c[7 ]; fC32=c32; fC33=c[9 ];
140 fC40=c[10]; fC41=c[11]; fC42=c42; fC43=c[13]; fC44=c[14];
141
0798b21e 142 if ((t.GetStatus()&AliESDtrack::kTIME) == 0) return;
83d73500 143 StartTimeIntegral();
144 Double_t times[10]; t.GetIntegratedTimes(times); SetIntegratedTimes(times);
145 SetIntegratedLength(t.GetIntegratedLength());
146}
147
73042f01 148//_____________________________________________________________________________
b19a0509 149AliTPCtrack::AliTPCtrack(const AliTPCtrack& t) : AliKalmanTrack(t) {
73042f01 150 //-----------------------------------------------------------------
151 // This is a track copy constructor.
152 //-----------------------------------------------------------------
be9c5115 153 fX=t.fX;
154 fAlpha=t.fAlpha;
73042f01 155 fdEdx=t.fdEdx;
156
be9c5115 157 fP0=t.fP0; fP1=t.fP1; fP2=t.fP2; fP3=t.fP3; fP4=t.fP4;
158
159 fC00=t.fC00;
160 fC10=t.fC10; fC11=t.fC11;
161 fC20=t.fC20; fC21=t.fC21; fC22=t.fC22;
162 fC30=t.fC30; fC31=t.fC31; fC32=t.fC32; fC33=t.fC33;
163 fC40=t.fC40; fC41=t.fC41; fC42=t.fC42; fC43=t.fC43; fC44=t.fC44;
164
165 Int_t n=GetNumberOfClusters();
166 for (Int_t i=0; i<n; i++) fIndex[i]=t.fIndex[i];
167}
9c9d2487 168//_____________________________________________________________________________
169
170void AliTPCtrack::GetBarrelTrack(AliBarrelTrack *track) {
171 //
172 // Create a Barrel Track out of this track
173 // Current track is propagated to the reference plane
174 // by the tracker
175 //
176 // [SR, 01.04.2003]
177
178 if (!track) return;
179 Double_t xr, vec[5], cov[15];
180
181 track->SetLabel(GetLabel());
182 track->SetX(fX, fAlpha);
183 track->SetNClusters(GetNumberOfClusters(), GetChi2());
2b5dc063 184 Double_t times[10];
185 GetIntegratedTimes(times);
186 track->SetTime(times, GetIntegratedLength());
9c9d2487 187
2b5dc063 188 track->SetMass(GetMass());
189 track->SetdEdX(GetdEdx());
9c9d2487 190
191 track->SetNWrongClusters(fNWrong);
192 track->SetNRotate(fNRotation);
be9c5115 193
9c9d2487 194 GetExternalParameters(xr, vec);
195 track->SetStateVector(vec);
196
197 GetExternalCovariance(cov);
198 track->SetCovarianceMatrix(cov);
199
200}
be9c5115 201//_____________________________________________________________________________
202Int_t AliTPCtrack::Compare(const TObject *o) const {
203 //-----------------------------------------------------------------
204 // This function compares tracks according to the their curvature
205 //-----------------------------------------------------------------
206 AliTPCtrack *t=(AliTPCtrack*)o;
024a7fe9 207 //Double_t co=TMath::Abs(t->Get1Pt());
208 //Double_t c =TMath::Abs(Get1Pt());
209 Double_t co=t->GetSigmaY2()*t->GetSigmaZ2();
210 Double_t c =GetSigmaY2()*GetSigmaZ2();
be9c5115 211 if (c>co) return 1;
212 else if (c<co) return -1;
213 return 0;
214}
215
216//_____________________________________________________________________________
217void AliTPCtrack::GetExternalCovariance(Double_t cc[15]) const {
218 //-------------------------------------------------------------------------
219 // This function returns an external representation of the covriance matrix.
220 // (See comments in AliTPCtrack.h about external track representation)
221 //-------------------------------------------------------------------------
9b280d80 222 Double_t a=GetConvConst();
be9c5115 223
b9de75e1 224 Double_t c22=fX*fX*fC44-2*fX*fC42+fC22;
225 Double_t c32=fX*fC43-fC32;
226 Double_t c20=fX*fC40-fC20, c21=fX*fC41-fC21, c42=fX*fC44-fC42;
be9c5115 227
228 cc[0 ]=fC00;
229 cc[1 ]=fC10; cc[2 ]=fC11;
230 cc[3 ]=c20; cc[4 ]=c21; cc[5 ]=c22;
b9de75e1 231 cc[6 ]=fC30; cc[7 ]=fC31; cc[8 ]=c32; cc[9 ]=fC33;
232 cc[10]=fC40*a; cc[11]=fC41*a; cc[12]=c42*a; cc[13]=fC43*a; cc[14]=fC44*a*a;
be9c5115 233
234}
235
236//_____________________________________________________________________________
237Double_t AliTPCtrack::GetPredictedChi2(const AliCluster *c) const
238{
239 //-----------------------------------------------------------------
240 // This function calculates a predicted chi2 increment.
241 //-----------------------------------------------------------------
242 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
243 r00+=fC00; r01+=fC10; r11+=fC11;
244
245 Double_t det=r00*r11 - r01*r01;
246 if (TMath::Abs(det) < 1.e-10) {
247 Int_t n=GetNumberOfClusters();
248 if (n>4) cerr<<n<<" AliKalmanTrack warning: Singular matrix !\n";
249 return 1e10;
250 }
251 Double_t tmp=r00; r00=r11; r11=tmp; r01=-r01;
252
253 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
254
255 return (dy*r00*dy + 2*r01*dy*dz + dz*r11*dz)/det;
73042f01 256}
257
c630aafd 258Double_t AliTPCtrack::GetYat(Double_t xk) const {
259//-----------------------------------------------------------------
260// This function calculates the Y-coordinate of a track at the plane x=xk.
261//-----------------------------------------------------------------
262 Double_t c1=fP4*fX - fP2, r1=TMath::Sqrt(1.- c1*c1);
263 Double_t c2=fP4*xk - fP2, r2=TMath::Sqrt(1.- c2*c2);
264 return fP0 + (xk-fX)*(c1+c2)/(r1+r2);
265}
266
73042f01 267//_____________________________________________________________________________
7f6ddf58 268Int_t AliTPCtrack::PropagateTo(Double_t xk,Double_t x0,Double_t rho) {
73042f01 269 //-----------------------------------------------------------------
270 // This function propagates a track to a reference plane x=xk.
271 //-----------------------------------------------------------------
1627d1c4 272 if (TMath::Abs(fP4*xk - fP2) >= 0.9) {
273 // Int_t n=GetNumberOfClusters();
274 //if (n>4) cerr<<n<<" AliTPCtrack warning: Propagation failed !\n";
73042f01 275 return 0;
276 }
e3f7105e 277
278 // old position for time [SR, GSI 17.02.2003]
279 Double_t oldX = fX;
280 Double_t oldY = fP0;
281 Double_t oldZ = fP1;
282 //
73042f01 283
b19a0509 284 Double_t x1=fX, x2=x1+(xk-x1), dx=x2-x1, y1=fP0, z1=fP1;
b9de75e1 285 Double_t c1=fP4*x1 - fP2, r1=sqrt(1.- c1*c1);
286 Double_t c2=fP4*x2 - fP2, r2=sqrt(1.- c2*c2);
73042f01 287
b19a0509 288 fP0 += dx*(c1+c2)/(r1+r2);
b9de75e1 289 fP1 += dx*(c1+c2)/(c1*r2 + c2*r1)*fP3;
73042f01 290
291 //f = F - 1
292 Double_t rr=r1+r2, cc=c1+c2, xx=x1+x2;
b19a0509 293 Double_t f02=-dx*(2*rr + cc*(c1/r1 + c2/r2))/(rr*rr);
b9de75e1 294 Double_t f04= dx*(rr*xx + cc*(c1*x1/r1+c2*x2/r2))/(rr*rr);
73042f01 295 Double_t cr=c1*r2+c2*r1;
b9de75e1 296 Double_t f12=-dx*fP3*(2*cr + cc*(c2*c1/r1-r1 + c1*c2/r2-r2))/(cr*cr);
297 Double_t f13= dx*cc/cr;
298 Double_t f14=dx*fP3*(cr*xx-cc*(r1*x2-c2*c1*x1/r1+r2*x1-c1*c2*x2/r2))/(cr*cr);
73042f01 299
300 //b = C*ft
b9de75e1 301 Double_t b00=f02*fC20 + f04*fC40, b01=f12*fC20 + f14*fC40 + f13*fC30;
302 Double_t b10=f02*fC21 + f04*fC41, b11=f12*fC21 + f14*fC41 + f13*fC31;
303 Double_t b20=f02*fC22 + f04*fC42, b21=f12*fC22 + f14*fC42 + f13*fC32;
304 Double_t b30=f02*fC32 + f04*fC43, b31=f12*fC32 + f14*fC43 + f13*fC33;
305 Double_t b40=f02*fC42 + f04*fC44, b41=f12*fC42 + f14*fC44 + f13*fC43;
73042f01 306
307 //a = f*b = f*C*ft
b9de75e1 308 Double_t a00=f02*b20+f04*b40,a01=f02*b21+f04*b41,a11=f12*b21+f14*b41+f13*b31;
73042f01 309
310 //F*C*Ft = C + (a + b + bt)
b19a0509 311 fC00 += a00 + 2*b00;
312 fC10 += a01 + b01 + b10;
313 fC20 += b20;
314 fC30 += b30;
315 fC40 += b40;
316 fC11 += a11 + 2*b11;
317 fC21 += b21;
318 fC31 += b31;
319 fC41 += b41;
73042f01 320
321 fX=x2;
322
323 //Multiple scattering******************
b19a0509 324 Double_t d=sqrt((x1-fX)*(x1-fX)+(y1-fP0)*(y1-fP0)+(z1-fP1)*(z1-fP1));
be9c5115 325 Double_t p2=(1.+ GetTgl()*GetTgl())/(Get1Pt()*Get1Pt());
7f6ddf58 326 Double_t beta2=p2/(p2 + GetMass()*GetMass());
024a7fe9 327 //Double_t theta2=14.1*14.1/(beta2*p2*1e6)*d/x0*rho;
328 Double_t theta2=1.0259e-6*10*10/20/(beta2*p2)*d*rho;
73042f01 329
b9de75e1 330 Double_t ey=fP4*fX - fP2, ez=fP3;
331 Double_t xz=fP4*ez, zz1=ez*ez+1, xy=fP2+ey;
73042f01 332
b19a0509 333 fC22 += (2*ey*ez*ez*fP2+1-ey*ey+ez*ez+fP2*fP2*ez*ez)*theta2;
b9de75e1 334 fC32 += ez*zz1*xy*theta2;
335 fC33 += zz1*zz1*theta2;
336 fC42 += xz*ez*xy*theta2;
337 fC43 += xz*zz1*theta2;
338 fC44 += xz*xz*theta2;
73042f01 339
340 //Energy losses************************
341 Double_t dE=0.153e-3/beta2*(log(5940*beta2/(1-beta2)) - beta2)*d*rho;
342 if (x1 < x2) dE=-dE;
b9de75e1 343 cc=fP4;
7f6ddf58 344 fP4*=(1.- sqrt(p2+GetMass()*GetMass())/p2*dE);
b9de75e1 345 fP2+=fX*(fP4-cc);
73042f01 346
e3f7105e 347 // Integrated Time [SR, GSI, 17.02.2003]
348 if (IsStartedTimeIntegral()) {
349 Double_t l2 = (fX-oldX)*(fX-oldX)+(fP0-oldY)*(fP0-oldY)+(fP1-oldZ)*(fP1-oldZ);
350 AddTimeStep(TMath::Sqrt(l2));
351 }
352 //
353
73042f01 354 return 1;
355}
356
357//_____________________________________________________________________________
7f6ddf58 358Int_t AliTPCtrack::PropagateToVertex(Double_t x0,Double_t rho)
73042f01 359{
360 //-----------------------------------------------------------------
361 // This function propagates tracks to the "vertex".
362 //-----------------------------------------------------------------
b9de75e1 363 Double_t c=fP4*fX - fP2;
364 Double_t tgf=-fP2/(fP4*fP0 + sqrt(1-c*c));
73042f01 365 Double_t snf=tgf/sqrt(1.+ tgf*tgf);
b9de75e1 366 Double_t xv=(fP2+snf)/fP4;
7f6ddf58 367 return PropagateTo(xv,x0,rho);
73042f01 368}
369
370//_____________________________________________________________________________
be9c5115 371Int_t AliTPCtrack::Update(const AliCluster *c, Double_t chisq, UInt_t index) {
73042f01 372 //-----------------------------------------------------------------
373 // This function associates a cluster with this track.
374 //-----------------------------------------------------------------
9c9d2487 375
376 // update the number of wrong SR[20.03.2003]
377 Int_t absLabel = TMath::Abs(GetLabel());
378 if ( (c->GetLabel(0) != absLabel) &&
379 (c->GetLabel(0) != absLabel) &&
380 (c->GetLabel(0) != absLabel)) fNWrong++;
381 //
382
73042f01 383 Double_t r00=c->GetSigmaY2(), r01=0., r11=c->GetSigmaZ2();
b19a0509 384 r00+=fC00; r01+=fC10; r11+=fC11;
73042f01 385 Double_t det=r00*r11 - r01*r01;
386 Double_t tmp=r00; r00=r11/det; r11=tmp/det; r01=-r01/det;
387
b19a0509 388 Double_t k00=fC00*r00+fC10*r01, k01=fC00*r01+fC10*r11;
389 Double_t k10=fC10*r00+fC11*r01, k11=fC10*r01+fC11*r11;
390 Double_t k20=fC20*r00+fC21*r01, k21=fC20*r01+fC21*r11;
391 Double_t k30=fC30*r00+fC31*r01, k31=fC30*r01+fC31*r11;
392 Double_t k40=fC40*r00+fC41*r01, k41=fC40*r01+fC41*r11;
73042f01 393
b19a0509 394 Double_t dy=c->GetY() - fP0, dz=c->GetZ() - fP1;
b9de75e1 395 Double_t cur=fP4 + k40*dy + k41*dz, eta=fP2 + k20*dy + k21*dz;
1627d1c4 396 if (TMath::Abs(cur*fX-eta) >= 0.9) {
397 // Int_t n=GetNumberOfClusters();
398 //if (n>4) cerr<<n<<" AliTPCtrack warning: Filtering failed !\n";
be9c5115 399 return 0;
73042f01 400 }
401
b19a0509 402 fP0 += k00*dy + k01*dz;
403 fP1 += k10*dy + k11*dz;
404 fP2 = eta;
b9de75e1 405 fP3 += k30*dy + k31*dz;
406 fP4 = cur;
73042f01 407
b19a0509 408 Double_t c01=fC10, c02=fC20, c03=fC30, c04=fC40;
409 Double_t c12=fC21, c13=fC31, c14=fC41;
73042f01 410
b19a0509 411 fC00-=k00*fC00+k01*fC10; fC10-=k00*c01+k01*fC11;
412 fC20-=k00*c02+k01*c12; fC30-=k00*c03+k01*c13;
413 fC40-=k00*c04+k01*c14;
73042f01 414
b19a0509 415 fC11-=k10*c01+k11*fC11;
416 fC21-=k10*c02+k11*c12; fC31-=k10*c03+k11*c13;
417 fC41-=k10*c04+k11*c14;
73042f01 418
b19a0509 419 fC22-=k20*c02+k21*c12; fC32-=k20*c03+k21*c13;
420 fC42-=k20*c04+k21*c14;
73042f01 421
b19a0509 422 fC33-=k30*c03+k31*c13;
b9de75e1 423 fC43-=k40*c03+k41*c13;
73042f01 424
b19a0509 425 fC44-=k40*c04+k41*c14;
73042f01 426
be9c5115 427 Int_t n=GetNumberOfClusters();
428 fIndex[n]=index;
429 SetNumberOfClusters(n+1);
430 SetChi2(GetChi2()+chisq);
431
432 return 1;
73042f01 433}
434
435//_____________________________________________________________________________
436Int_t AliTPCtrack::Rotate(Double_t alpha)
437{
438 //-----------------------------------------------------------------
439 // This function rotates this track.
440 //-----------------------------------------------------------------
9c9d2487 441
442 if (alpha != 0) fNRotation++; // [SR, 01.04.2003]
443
73042f01 444 fAlpha += alpha;
be9c5115 445 if (fAlpha<-TMath::Pi()) fAlpha += 2*TMath::Pi();
446 if (fAlpha>=TMath::Pi()) fAlpha -= 2*TMath::Pi();
73042f01 447
b19a0509 448 Double_t x1=fX, y1=fP0;
73042f01 449 Double_t ca=cos(alpha), sa=sin(alpha);
b9de75e1 450 Double_t r1=fP4*fX - fP2;
73042f01 451
452 fX = x1*ca + y1*sa;
b19a0509 453 fP0=-x1*sa + y1*ca;
b9de75e1 454 fP2=fP2*ca + (fP4*y1 + sqrt(1.- r1*r1))*sa;
73042f01 455
b9de75e1 456 Double_t r2=fP4*fX - fP2;
73042f01 457 if (TMath::Abs(r2) >= 0.99999) {
be9c5115 458 Int_t n=GetNumberOfClusters();
459 if (n>4) cerr<<n<<" AliTPCtrack warning: Rotation failed !\n";
73042f01 460 return 0;
461 }
462
b9de75e1 463 Double_t y0=fP0 + sqrt(1.- r2*r2)/fP4;
464 if ((fP0-y0)*fP4 >= 0.) {
be9c5115 465 Int_t n=GetNumberOfClusters();
466 if (n>4) cerr<<n<<" AliTPCtrack warning: Rotation failed !!!\n";
73042f01 467 return 0;
468 }
469
470 //f = F - 1
b9de75e1 471 Double_t f00=ca-1, f24=(y1 - r1*x1/sqrt(1.- r1*r1))*sa,
472 f20=fP4*sa, f22=(ca + sa*r1/sqrt(1.- r1*r1))-1;
73042f01 473
474 //b = C*ft
b9de75e1 475 Double_t b00=fC00*f00, b02=fC00*f20+fC40*f24+fC20*f22;
476 Double_t b10=fC10*f00, b12=fC10*f20+fC41*f24+fC21*f22;
477 Double_t b20=fC20*f00, b22=fC20*f20+fC42*f24+fC22*f22;
478 Double_t b30=fC30*f00, b32=fC30*f20+fC43*f24+fC32*f22;
479 Double_t b40=fC40*f00, b42=fC40*f20+fC44*f24+fC42*f22;
73042f01 480
481 //a = f*b = f*C*ft
b9de75e1 482 Double_t a00=f00*b00, a02=f00*b02, a22=f20*b02+f24*b42+f22*b22;
73042f01 483
484 // *** Double_t dy2=fCyy;
485
486 //F*C*Ft = C + (a + b + bt)
b19a0509 487 fC00 += a00 + 2*b00;
488 fC10 += b10;
489 fC20 += a02+b20+b02;
490 fC30 += b30;
491 fC40 += b40;
492 fC21 += b12;
493 fC32 += b32;
494 fC22 += a22 + 2*b22;
495 fC42 += b42;
73042f01 496
497 // *** fCyy+=dy2*sa*sa*r1*r1/(1.- r1*r1);
498 // *** fCzz+=d2y*sa*sa*fT*fT/(1.- r1*r1);
499
500 return 1;
501}
502
b9de75e1 503void AliTPCtrack::ResetCovariance() {
504 //------------------------------------------------------------------
505 //This function makes a track forget its history :)
506 //------------------------------------------------------------------
507
508 fC00*=10.;
509 fC10=0.; fC11*=10.;
510 fC20=0.; fC21=0.; fC22*=10.;
511 fC30=0.; fC31=0.; fC32=0.; fC33*=10.;
512 fC40=0.; fC41=0.; fC42=0.; fC43=0.; fC44*=10.;
513
73042f01 514}
77e58468 515
516////////////////////////////////////////////////////////////////////////
517Double_t AliTPCtrack::Phi() const {
7c27857f 518//
519//
520//
77e58468 521 Double_t phi = TMath::ASin(GetSnp()) + fAlpha;
522 if (phi<0) phi+=2*TMath::Pi();
523 if (phi>=2*TMath::Pi()) phi-=2*TMath::Pi();
524 return phi;
525}
526////////////////////////////////////////////////////////////////////////
527