Initialization of persistent data members
[u/mrichter/AliRoot.git] / STEER / AliKalmanTrack.cxx
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87594435 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
acd84897 16/* $Id$ */
fb17acd4 17
87594435 18//-------------------------------------------------------------------------
19// Implementation of the AliKalmanTrack class
066782e8 20// that is the base for AliTPCtrack, AliITStrackV2 and AliTRDtrack
87594435 21// Origin: Iouri Belikov, CERN, Jouri.Belikov@cern.ch
22//-------------------------------------------------------------------------
23
24#include "AliKalmanTrack.h"
f37d970d 25#include "AliLog.h"
87594435 26
27ClassImp(AliKalmanTrack)
28
116cbefd 29Double_t AliKalmanTrack::fgConvConst;
9b280d80 30
e2afb3b6 31//_______________________________________________________________________
32AliKalmanTrack::AliKalmanTrack():
33 fLab(-3141593),
68b8060b 34 fFakeRatio(0),
e2afb3b6 35 fChi2(0),
304864ab 36 fMass(AliPID::ParticleMass(AliPID::kPion)),
e2afb3b6 37 fN(0)
38{
116cbefd 39 //
40 // Default constructor
41 //
8de97894 42 if (fgConvConst==0) {
f37d970d 43 AliFatal("The magnetic field has not been set!");
8de97894 44 }
74f9526e 45
46 fStartTimeIntegral = kFALSE;
47 fIntegratedLength = 0;
48 for(Int_t i=0; i<5; i++) fIntegratedTime[i] = 0;
e2afb3b6 49}
50
51//_______________________________________________________________________
52AliKalmanTrack::AliKalmanTrack(const AliKalmanTrack &t):
53 TObject(t),
54 fLab(t.fLab),
babd135a 55 fFakeRatio(t.fFakeRatio),
e2afb3b6 56 fChi2(t.fChi2),
57 fMass(t.fMass),
58 fN(t.fN)
59{
116cbefd 60 //
61 // Copy constructor
62 //
8de97894 63 if (fgConvConst==0) {
f37d970d 64 AliFatal("The magnetic field has not been set!");
8de97894 65 }
74f9526e 66
67 fStartTimeIntegral = t.fStartTimeIntegral;
68 fIntegratedLength = t.fIntegratedLength;
69
70 for (Int_t i=0; i<5; i++)
71 fIntegratedTime[i] = t.fIntegratedTime[i];
72}
c5507f6d 73
74f9526e 74//_______________________________________________________________________
75void AliKalmanTrack::StartTimeIntegral()
76{
49a7a79a 77 // Sylwester Radomski, GSI
78 // S.Radomski@gsi.de
74f9526e 79 //
80 // Start time integration
81 // To be called at Vertex by ITS tracker
82 //
83
84 //if (fStartTimeIntegral)
f37d970d 85 // AliWarning("Reseting Recorded Time.");
74f9526e 86
87 fStartTimeIntegral = kTRUE;
304864ab 88 for(Int_t i=0; i<AliPID::kSPECIES; i++) fIntegratedTime[i] = 0;
74f9526e 89 fIntegratedLength = 0;
90}
91//_______________________________________________________________________
92void AliKalmanTrack:: AddTimeStep(Double_t length)
93{
94 //
95 // Add step to integrated time
96 // this method should be called by a sublasses at the end
97 // of the PropagateTo function or by a tracker
98 // each time step is made.
99 //
100 // If integration not started function does nothing
101 //
102 // Formula
103 // dt = dl * sqrt(p^2 + m^2) / p
104 // p = pT * (1 + tg^2 (lambda) )
105 //
106 // pt = 1/external parameter [4]
107 // tg lambda = external parameter [3]
108 //
109 //
110 // Sylwester Radomski, GSI
111 // S.Radomski@gsi.de
112 //
113
5d8718b8 114 static const Double_t kcc = 2.99792458e-2;
74f9526e 115
116 if (!fStartTimeIntegral) return;
117
118 fIntegratedLength += length;
119
74f9526e 120 Double_t xr, param[5];
121 Double_t pt, tgl;
122
123 GetExternalParameters(xr, param);
124 pt = 1/param[4] ;
125 tgl = param[3];
126
127 Double_t p = TMath::Abs(pt * TMath::Sqrt(1+tgl*tgl));
128
129 if (length > 100) return;
130
304864ab 131 for (Int_t i=0; i<AliPID::kSPECIES; i++) {
74f9526e 132
304864ab 133 Double_t mass = AliPID::ParticleMass(i);
74f9526e 134 Double_t correction = TMath::Sqrt( pt*pt * (1 + tgl*tgl) + mass * mass ) / p;
5d8718b8 135 Double_t time = length * correction / kcc;
74f9526e 136
74f9526e 137 fIntegratedTime[i] += time;
138 }
e2afb3b6 139}
140
74f9526e 141//_______________________________________________________________________
142
143Double_t AliKalmanTrack::GetIntegratedTime(Int_t pdg) const
144{
49a7a79a 145 // Sylwester Radomski, GSI
146 // S.Radomski@gsi.de
74f9526e 147 //
148 // Return integrated time hypothesis for a given particle
149 // type assumption.
150 //
151 // Input parameter:
152 // pdg - Pdg code of a particle type
153 //
154
155
156 if (!fStartTimeIntegral) {
f37d970d 157 AliWarning("Time integration not started");
74f9526e 158 return 0.;
159 }
160
304864ab 161 for (Int_t i=0; i<AliPID::kSPECIES; i++)
162 if (AliPID::ParticleCode(i) == TMath::Abs(pdg)) return fIntegratedTime[i];
74f9526e 163
f37d970d 164 AliWarning(Form("Particle type [%d] not found", pdg));
74f9526e 165 return 0;
166}
ae982df3 167
168void AliKalmanTrack::GetIntegratedTimes(Double_t *times) const {
304864ab 169 for (Int_t i=0; i<AliPID::kSPECIES; i++) times[i]=fIntegratedTime[i];
ae982df3 170}
171
172void AliKalmanTrack::SetIntegratedTimes(const Double_t *times) {
304864ab 173 for (Int_t i=0; i<AliPID::kSPECIES; i++) fIntegratedTime[i]=times[i];
ae982df3 174}
175
74f9526e 176//_______________________________________________________________________
177
178void AliKalmanTrack::PrintTime() const
179{
49a7a79a 180 // Sylwester Radomski, GSI
181 // S.Radomski@gsi.de
182 //
74f9526e 183 // For testing
184 // Prints time for all hypothesis
185 //
186
304864ab 187 for (Int_t i=0; i<AliPID::kSPECIES; i++)
188 printf("%d: %.2f ", AliPID::ParticleCode(i), fIntegratedTime[i]);
74f9526e 189 printf("\n");
190}
191
49a7a79a 192static void External2Helix(const AliKalmanTrack *t, Double_t helix[6]) {
193 //--------------------------------------------------------------------
194 // External track parameters -> helix parameters
195 //--------------------------------------------------------------------
196 Double_t alpha,x,cs,sn;
197 t->GetExternalParameters(x,helix); alpha=t->GetAlpha();
198
199 cs=TMath::Cos(alpha); sn=TMath::Sin(alpha);
200 helix[5]=x*cs - helix[0]*sn; // x0
201 helix[0]=x*sn + helix[0]*cs; // y0
202//helix[1]= // z0
203 helix[2]=TMath::ASin(helix[2]) + alpha; // phi0
204//helix[3]= // tgl
205 helix[4]=helix[4]/t->GetConvConst(); // C
206}
207
208static void Evaluate(const Double_t *h, Double_t t,
209 Double_t r[3], //radius vector
210 Double_t g[3], //first defivatives
211 Double_t gg[3]) //second derivatives
212{
213 //--------------------------------------------------------------------
214 // Calculate position of a point on a track and some derivatives
215 //--------------------------------------------------------------------
216 Double_t phase=h[4]*t+h[2];
217 Double_t sn=TMath::Sin(phase), cs=TMath::Cos(phase);
218
219 r[0] = h[5] + (sn - h[6])/h[4];
220 r[1] = h[0] - (cs - h[7])/h[4];
221 r[2] = h[1] + h[3]*t;
222
223 g[0] = cs; g[1]=sn; g[2]=h[3];
224
225 gg[0]=-h[4]*sn; gg[1]=h[4]*cs; gg[2]=0.;
226}
227
228Double_t AliKalmanTrack::
229GetDCA(const AliKalmanTrack *p, Double_t &xthis, Double_t &xp) const {
230 //------------------------------------------------------------
231 // Returns the (weighed !) distance of closest approach between
232 // this track and the track passed as the argument.
233 // Other returned values:
234 // xthis, xt - coordinates of tracks' reference planes at the DCA
235 //-----------------------------------------------------------
236 Double_t dy2=GetSigmaY2() + p->GetSigmaY2();
237 Double_t dz2=GetSigmaZ2() + p->GetSigmaZ2();
238 Double_t dx2=dy2;
239
240 //dx2=dy2=dz2=1.;
241
242 Double_t p1[8]; External2Helix(this,p1);
243 p1[6]=TMath::Sin(p1[2]); p1[7]=TMath::Cos(p1[2]);
244 Double_t p2[8]; External2Helix(p,p2);
245 p2[6]=TMath::Sin(p2[2]); p2[7]=TMath::Cos(p2[2]);
246
247
248 Double_t r1[3],g1[3],gg1[3]; Double_t t1=0.;
249 Evaluate(p1,t1,r1,g1,gg1);
250 Double_t r2[3],g2[3],gg2[3]; Double_t t2=0.;
251 Evaluate(p2,t2,r2,g2,gg2);
74f9526e 252
49a7a79a 253 Double_t dx=r2[0]-r1[0], dy=r2[1]-r1[1], dz=r2[2]-r1[2];
254 Double_t dm=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2;
255
256 Int_t max=27;
257 while (max--) {
258 Double_t gt1=-(dx*g1[0]/dx2 + dy*g1[1]/dy2 + dz*g1[2]/dz2);
259 Double_t gt2=+(dx*g2[0]/dx2 + dy*g2[1]/dy2 + dz*g2[2]/dz2);
260 Double_t h11=(g1[0]*g1[0] - dx*gg1[0])/dx2 +
261 (g1[1]*g1[1] - dy*gg1[1])/dy2 +
262 (g1[2]*g1[2] - dz*gg1[2])/dz2;
263 Double_t h22=(g2[0]*g2[0] + dx*gg2[0])/dx2 +
264 (g2[1]*g2[1] + dy*gg2[1])/dy2 +
265 (g2[2]*g2[2] + dz*gg2[2])/dz2;
266 Double_t h12=-(g1[0]*g2[0]/dx2 + g1[1]*g2[1]/dy2 + g1[2]*g2[2]/dz2);
267
268 Double_t det=h11*h22-h12*h12;
269
270 Double_t dt1,dt2;
271 if (TMath::Abs(det)<1.e-33) {
272 //(quasi)singular Hessian
273 dt1=-gt1; dt2=-gt2;
274 } else {
275 dt1=-(gt1*h22 - gt2*h12)/det;
276 dt2=-(h11*gt2 - h12*gt1)/det;
277 }
278
279 if ((dt1*gt1+dt2*gt2)>0) {dt1=-dt1; dt2=-dt2;}
280
281 //check delta(phase1) ?
282 //check delta(phase2) ?
283
284 if (TMath::Abs(dt1)/(TMath::Abs(t1)+1.e-3) < 1.e-4)
285 if (TMath::Abs(dt2)/(TMath::Abs(t2)+1.e-3) < 1.e-4) {
286 if ((gt1*gt1+gt2*gt2) > 1.e-4/dy2/dy2)
f37d970d 287 AliWarning(" stopped at not a stationary point !");
49a7a79a 288 Double_t lmb=h11+h22; lmb=lmb-TMath::Sqrt(lmb*lmb-4*det);
289 if (lmb < 0.)
f37d970d 290 AliWarning(" stopped at not a minimum !");
49a7a79a 291 break;
292 }
293
294 Double_t dd=dm;
295 for (Int_t div=1 ; ; div*=2) {
296 Evaluate(p1,t1+dt1,r1,g1,gg1);
297 Evaluate(p2,t2+dt2,r2,g2,gg2);
298 dx=r2[0]-r1[0]; dy=r2[1]-r1[1]; dz=r2[2]-r1[2];
299 dd=dx*dx/dx2 + dy*dy/dy2 + dz*dz/dz2;
300 if (dd<dm) break;
301 dt1*=0.5; dt2*=0.5;
302 if (div>512) {
f37d970d 303 AliWarning(" overshoot !"); break;
49a7a79a 304 }
305 }
306 dm=dd;
307
308 t1+=dt1;
309 t2+=dt2;
310
311 }
312
f37d970d 313 if (max<=0) AliWarning(" too many iterations !");
49a7a79a 314
315 Double_t cs=TMath::Cos(GetAlpha());
316 Double_t sn=TMath::Sin(GetAlpha());
317 xthis=r1[0]*cs + r1[1]*sn;
318
319 cs=TMath::Cos(p->GetAlpha());
320 sn=TMath::Sin(p->GetAlpha());
321 xp=r2[0]*cs + r2[1]*sn;
322
323 return TMath::Sqrt(dm*TMath::Sqrt(dy2*dz2));
324}
325
326Double_t AliKalmanTrack::
327PropagateToDCA(AliKalmanTrack *p, Double_t d, Double_t x0) {
328 //--------------------------------------------------------------
329 // Propagates this track and the argument track to the position of the
330 // distance of closest approach.
331 // Returns the (weighed !) distance of closest approach.
332 //--------------------------------------------------------------
333 Double_t xthis,xp;
334 Double_t dca=GetDCA(p,xthis,xp);
335
336 if (!PropagateTo(xthis,d,x0)) {
f37d970d 337 //AliWarning(" propagation failed !");
49a7a79a 338 return 1e+33;
339 }
340
341 if (!p->PropagateTo(xp,d,x0)) {
f37d970d 342 //AliWarning(" propagation failed !";
49a7a79a 343 return 1e+33;
344 }
345
346 return dca;
347}